Group IVA functionalized particles and methods of use thereof

ABSTRACT

Disclosed are functionalized Group IVA particles, methods of preparing the Group IVA particles, and methods of using the Group IVA particles. The Group IVA particles may be passivated with at least one layer of material covering at least a portion of the particle. The layer of material may be a covalently bonded non-dielectric layer of material. The Group IVA particles may be used in various technologies, including lithium ion batteries and photovoltaic cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 13/972,575,filed on Aug. 21, 2013, which claims priority to U.S. Provisional PatentApplication No. 61/691,641, filed on Aug. 21, 2012, U.S. ProvisionalPatent Application No. 61/773,270, filed on Mar. 6, 2013, and U.S.Provisional Patent Application No. 61/815,654, filed on Apr. 24, 2013,the entire contents of all of which are fully incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates generally to functionalized Group IVAparticles, and more particularly, to Group IVA particles passivated by acovalently bonded non-dielectric layer of hydrocarbons, methods ofpreparing the Group IVA particles, and methods of using the Group IVAparticles. The present disclosure also relates to the incorporation ofporous covalent frameworks with covalently bound Group IVA particles,and methods of using the porous covalent frameworks in batterytechnologies.

BACKGROUND

A battery is an electrochemical energy storage device. Batteries can becategorized as either primary (non-rechargeable) or secondary(rechargeable). In either case, a fully charged battery deliverselectrical power as it undergoes an oxidation/reduction process andelectrons are allowed to flow between the negative and positive polls ofthe battery.

Lithium ion batteries can be made as secondary batteries; which meansthat they can be recharged by driving current in the opposite directionand reducing lithium ions to Li⁰ at the anode. A generalized schematicrepresentation of a lithium ion battery is shown in FIG. 1. Thedirection of movement of ions and electrons are shown to represent“charging”. The discharge cycle would show ions moving in the oppositedirection. Lithium ions migrating into the anode are met by electronsmoving toward the anode through the closed circuit, thus reducing theLi⁺ to Li⁰ (lithium metal). Li⁰ is actually much larger in diameter thanLi⁺ because of the electron it acquired occupies its 2S orbital.Consequently lithium metal occupies a significant amount of space.Conventional carbon anodes accommodate reduced lithium between thelayers of graphite. Graphite can be thought of as 2-D arrays of6-membered rings of carbon forming “sheets” that slide easily on oneanother. Fully charged, a graphite anode is able to accommodate thevolume of lithium without imposing special demands beyond the inherentspace that already exists between the sheets of graphite sheets.

There are no such special demands on the cathode as Li⁺ requires verylittle space (like adding sand to a bucket of gravel). The metal oxidesand/or phosphates comprising the cathode stay in place. But only afinite number of Li⁺ ions (usually one or two) can pair with eachcluster of metal oxides. Thus much greater space requirement of thecathode limits the specific charge capacity (charge per gram or chargeper cubic millimeter). From the standpoint of size and molecular massalone, lithium is the ideal element to use in batteries that must bemade compact and light. In addition, lithium has the highest redoxpotential difference of any element.

The average cathode composition generally has lower charge capacity andtherefore requires more size (and weight) when matched with the mostcommon anode composite, graphite. As a consequence, a majority ofresearch has focused on developing improved cathodes.

Some researchers have sought to develop alternative anodes for lithiumion batteries using silicon based materials. Silicon (Si) is known tohave a far superior capacity to attract lithium than carbon used intraditional batteries [372 milliamp hours per gram, (mAh/g) versus 4,212mAh/g for Si]. However, no commercial batteries have been successfullyintroduced using Si because no suitable structure has been found thatprevents mechanical breakdown of the Si composites after only a fewrecharge cycles. Specifically, the limited structural form of silicon,coupled with the strong attraction that lithium has for silicon, resultsin mechanical failure due to volumetric expansion after a fewcharge/recharge cycles.

Accordingly, there is a need for new materials and methods that improveupon existing battery technology. In particular, there is a need formaterials that provide a suitable porous framework to accommodate thespatial requirements of lithium accumulation at the anode of lithium ionbatteries, and also possess good charge carrier mobility.

Also needed are nanoparticle materials that can be efficiently andeconomically produced from abundant and readily available raw materials.While particle size control has been demonstrated using suchmethodologies as plasma enhanced chemical vapor deposition (PECVD), hotwire chemical vapor deposition (HWCVD) and ion beam deposition (IBD),commercial production using these methods usually involve in situ filmmanufacturing. Group IVA nanoparticle powders are only availablecommercially in very limited range of specifications and only withdielectric passivation. The products are expensive because theirproduction requires large capital costs for production equipment andhigh energy costs in production.

SUMMARY

In one aspect, disclosed is a functionalized Group IVA particle. TheGroup IVA particle may be passivated by a non-dielectric layer coveringat least a portion of a surface of the Group IVA particle.

The non-dielectric layer may be derived from a compound selected fromthe group consisting of alkenes, alkynes, aromatics, heteroaromatics,cycloalkenes, alcohols, glycols, thiols, disulfides, amines, amides,pyridines, pyrrols, furans, thiophenes, cyanates, isocyanates,isothiocyanates, ketones, carboxylic acids, amino acids, and aldehydes.The non-dielectric layer may be derived from a compound selected fromthe group consisting toluene, benzene, a polycyclic aromatic, afullerene, a metallofullerene, a styrene, a cyclooctatetraene, anorbornadiene, a primary alkene, a primary alkyne, a saturated orunsaturated fatty acid, a peptide, a protein, an enzyme,2,3,6,7-tetrahydroxyanthracene, and terephthalaldehyde. Thenon-dielectric layer may possess functional groups capable of formingcovalent bonds to other reagents.

In certain embodiments, the Group IVA particle is stable to oxidation inair at room temperature.

In certain embodiments, the Group IVA particle is 25 microns in size orless, 1 micron in size or less, 0.1 micron in size or less, or 0.05micron in size or less.

In certain embodiments, the Group IVA particle is covalently bonded to aporous covalent framework. The porous covalent framework may be acovalent organic framework, a metal organic framework, or a zeoliticimidazolate framework. The porous covalent framework may be a2-dimensional framework. The porous covalent framework may be a3-dimensional framework.

In certain embodiments, the Group IVA particle comprises silicon,germanium, tin, or any combination thereof. The Group IVA particle maycomprise an n-type dopant or a p-type dopant. The n-type dopant maycomprise nitrogen, phosphorous, arsenic, or any combination thereof. Thep-type dopant may comprise boron, aluminum, or any combination thereof.The Group IVA particle may comprise an impurity selected from the groupconsisting of aluminum, iron, calcium, and titanium.

In certain embodiments, the Group IVA particle may be derived frommetallurgical grade silicon. The Group IVA particle may be derived froma p-type silicon wafer, wherein the p-type silicon wafer may have ameasured resistivity of 0.001-100 ohm/cm². The Group IVA particle may bederived from an n-type silicon wafer. The Group IVA particle may bederived from bulk MG Group IVA ingot material.

In certain embodiments, the Group IVA particle may be part of an anodein a lithium ion battery, part of a photovoltaic (PV) film, part of abiosensor, part of an energy storage device, part of a thermoelectricfilm, or part of a semiconductor device.

In certain embodiments, the Group IVA particle may be prepared by aprocess comprising the steps of: treating a Group IVA particle with aprotic acid to provide a hydrogen passivated Group IVA particle; andtreating the hydrogen passivated Group IVA particle with a compound toprovide a passivated Group IVA particle. In certain embodiments, theGroup IVA particle may be prepared by a process comprising the steps of:treating a Group IVA particle with a protic acid to provide a hydrogenpassivated Group IVA particle; treating the hydrogen passivated GroupIVA particle with benzene to yield a benzene passivated Group IVAparticle; and treating the benzene passivated Group IVA particle with acompound to provide a passivated Group IVA particle. In certainembodiments, the passivated Group IVA particle may be a particlepassivated with a non-dielectric layer covering at least a portion of asurface of the Group IVA particle. In certain embodiments, thepassivated Group IVA particle may be stable to oxidation in air at roomtemperature. The compound for passivating may be selected from the groupconsisting of an organic compound, a fullerene, and an organometalliccompound.

In certain embodiments, the Group IVA particle possesses functionalgroups capable of forming covalent bonds to other reagents.

In another aspect, disclosed are methods of preparing functionalizedGroup IVA particles.

In certain embodiments, a method of functionalizing a Group IVA particlecomprises treating a Group IVA particle with a protic acid to provide ahydrogen passivated Group IVA particle; and treating the hydrogenpassivated Group IVA particle with a compound to provide a passivatedGroup IVA particle. In certain embodiments, a method of functionalizinga Group IVA particle comprises treating a Group IVA particle with aprotic acid to provide a hydrogen passivated Group IVA particle;treating the hydrogen passivated Group IVA particle with benzene toyield a stable benzene passivated Group IVA particle; and treating thebenzene passivated Group IVA particle with a compound to provide apassivated Group IVA particle. The passivated Group IVA particles may bestable to oxidation in air at room temperature. The passivated Group IVAparticles may be passivated with a non-dielectric layer covering atleast a portion of a surface of the Group IVA particle.

In certain embodiments, a method of functionalizing a Group IVA particlecomprises comminuting a material comprising a Group IVA element in asolvent comprising benzene to yield a benzene passivated Group IVAparticle; and treating the benzene passivated Group IVA particle with acompound to provide a passivated Group IVA particle.

In certain embodiments, a method of functionalizing a Group IVA particlecomprises comminuting a material comprising a Group IVA element in thepresence of a compound to provide a passivated Group IVA particle.

In certain embodiments, the compound used for passivation may beselected from the group consisting of alkenes, alkynes, aromatics,heteroaromatics, cycloalkenes, alcohols, glycols, thiols, disulfides,amines, amides, pyridines, pyrrols, furans, thiophenes, cyanates,isocyanates, isothiocyanates, ketones, carboxylic acids, amino acids,and aldehydes. In certain embodiments, the compound used for passivationmay be selected from the group consisting toluene, benzene, a polycyclicaromatic, a fullerene, a metallofullerene, a styrene, acyclooctatetraene, a norbornadiene, a primary alkene, a primary alkyne,a saturated or unsaturated fatty acid, a peptide, a protein, an enzyme,2,3,6,7-tetrahydroxyanthracene, and terephthalaldehyde.

In certain embodiments, the passivated Group IVA particle possessesfunctional groups capable of forming covalent bonds to other reagents.

In certain embodiments, the Group IVA particle is 25 microns in size orless, 1 micron in size or less, 0.1 micron in size or less, or 0.05micron in size or less.

In certain embodiments, the Group IVA particle is covalently bonded to aporous covalent framework. The porous covalent framework may be acovalent organic framework, a metal organic framework, or a zeoliticimidazolate framework. The porous covalent framework may be a2-dimensional framework. The porous covalent framework may be a3-dimensional framework.

In certain embodiments, the Group IVA particle comprises silicon,germanium, tin, or any combination thereof. The Group IVA particle maycomprise an n-type dopant or a p-type dopant. The n-type dopant maycomprise nitrogen, phosphorous, arsenic, or any combination thereof. Thep-type dopant may comprise boron, aluminum, or any combination thereof.The Group IVA particle may comprise an impurity selected from the groupconsisting of aluminum, iron, calcium, and titanium.

In certain embodiments, the Group IVA particle may be part of an anodein a lithium ion battery, part of a sorbent for capturing mercury from acombustion gas, part of a photovoltaic (PV) film, part of a biosensor,part of an energy storage device, part of a thermoelectric film, or partof a semiconductor device.

In certain embodiments, the protic acid may be selected from the groupconsisting of nitric acid, hydrochloric acid, hydrofluoric acid, andhydrobromic acid.

In certain embodiments, the synthetic steps to prepare the passivatedGroup IVA particles are conducted at about room temperature.

In certain embodiments, the Group IVA particle may be derived frommetallurgical grade silicon. The Group IVA particle may be derived froma p-type silicon wafer, wherein the p-type silicon wafer may have ameasured resistivity of 0.001-100 ohm/cm². The Group IVA particle may bederived from an n-type silicon wafer. The Group IVA particle may bederived from bulk MG Group IVA ingot material.

In certain embodiments, prior to treating the Group IVA particle withprotic acid, the method comprises crushing, grinding, and milling aningot or wafer material comprising a Group IVA element to providesubmicron Group IVA particles ready for passivation.

In certain embodiments, the methods of preparing the Group IVA particlesare a non-clean room processes.

In another aspect, disclosed is a lithium ion battery comprising: apositive electrode; a negative electrode comprising a compositecomprising at least one submicron functionalized Group IVA particle(e.g., a conductive, porous covalent framework comprising at least onesubmicron functionalized Group IVA particle covalently bonded to theframework); a lithium ion permeable separator between the positiveelectrode and the negative electrode; and an electrolyte comprisinglithium ions. The porous covalent framework may be a covalent organicframework, a metal organic framework, or a zeolitic imidazolateframework. The porous covalent framework may be a 2-dimensionalframework or a 3-dimensional framework. In certain embodiments, thelithium ion battery includes a solvent that is a mixture of at leastethylene and propylene carbonates.

The compositions, methods and processes are further described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 depicts a generalized schematic representation of a lithium ionbattery.

FIG. 2 depicts a simplified representation of passivated Group IVAparticles.

FIG. 3 depicts a simplified representation of a modification reactionfrom particle 2 to particle 3.

FIG. 4 depicts Group IVA nanoparticles functionalized with2,3,6,7-tetrahydroxyl-anthracene groups.

FIG. 5 depicts one exemplary process for preparing functionalized GroupIVA particles.

FIG. 6 depicts one exemplary composite for c-Si conductive films.

FIG. 7 depicts a lithium ion battery using a silicon-covalent porousframework anode.

FIG. 8 depicts a simplified representation of an anode materialincluding functionalized Group IVA particles.

FIG. 9 depicts a simplified representation of an anode materialincluding functionalized Group IVA particles and a conductive adhesionadditive.

FIG. 10 depicts a simplified representation of an anode materialincluding functionalized Group IVA particles, and a conductive adhesionadditive and/or a dopant additive.

FIG. 11 depicts a porous framework composite including functionalizedGroup IVA particles.

FIG. 12 depicts one exemplary process for preparing a battery includingfunctionalized Group IVA particles.

FIG. 13 depicts an exemplary copper substrate to which a conductive inkwas applied.

FIG. 14 depicts a die cutter useful for preparing disc anodes from asubstrate.

FIG. 15a depicts a photograph of a disc anode prepared withfunctionalized Group IVA particles.

FIG. 15b depicts a photograph at 40× magnification of a disc anodeprepared with functionalized Group IVA particles.

FIG. 15c depicts a photograph at 100× magnification of a disc anodeprepared with functionalized Group IVA particles.

FIG. 16 depicts a controlled atmosphere glovebox with coin cellassembling equipment.

FIG. 17 depicts a schematic diagram of a photovoltaic cell including asemiconductor film incorporating functionalized Group IVA particles.

FIG. 18 depicts an Energy Dispersive X-ray Spectrum showing resolvedK-alpha signals that include Si, O, and C.

FIG. 19 depicts an Energy Dispersive X-ray Spectrum of benzenefunctionalized nc-Si (ca. 300 nm) following removal of excess benzene.

FIG. 20 depicts a SEM image of nc-Si particles functionalized withbenzene.

FIG. 21 depicts a FTIR spectrum of nc-Si particles functionalized withbenzene.

FIG. 22a depicts a TGA scan of benzene passivated nc-Si (estimated APS300 nm or less) at 30° C./min.

FIG. 22b depicts a TGA scan of benzene passivated nc-Si (estimated APS300 nm or less) at 10° C./min.

FIG. 23 depicts a charge/discharge plot.

FIG. 24 depicts a charge/discharge plot.

FIG. 25 depicts a charge capacity plot.

FIG. 26 depicts a charge/discharge plot.

FIG. 27 depicts a charge capacity plot.

FIG. 28 depicts a charge/discharge plot.

FIG. 29 depicts a charge capacity plot.

FIG. 30 depicts a charge/discharge plot.

FIG. 31 depicts a charge capacity plot.

FIG. 32 depicts a charge/discharge plot.

FIG. 33 depicts a charge capacity plot.

FIG. 34 depicts a charge/discharge plot.

FIG. 35 depicts a charge capacity plot.

FIG. 36 depicts a charge/discharge plot.

FIG. 37 depicts a charge capacity plot.

FIG. 38 depicts a charge/discharge plot.

FIG. 39 depicts a charge/discharge plot.

FIG. 40 depicts a charge/discharge plot.

FIG. 41 depicts a charge/discharge plot.

FIG. 42 depicts a comparison of lithium ion batteries prepared withanodes including functionalized Group IVA particles versus batteriesprepared with a standard carbon based anode.

FIG. 43 depicts a correlation between resistance and specific chargecapacity.

DETAILED DESCRIPTION

Disclosed herein are micron and submicron sized, passivated Group IVAparticles; methods of preparing the Group IVA particles; and methods ofusing the Group IVA particles. Also disclosed are compositionscomprising the Group IVA particles, such as inks or pastes comprisingthe Group IVA particles. Also disclosed are anodes and batteriescomprising the Group IVA particles.

The Group IVA particles, the methods of preparing said particles, andmethods of using said particles, as disclosed herein, provide severaladvantages over current technologies and practices. As one advantage,the Group IVA particles may be efficiently and economically producedfrom readily available starting materials. The Group IV particles can beprepared on a large scale and commercialized in an inexpensiveindustrial process. For example, the Group IVA particles can be made andfunctionalized without the use of heat or other high energy processes,thereby lowering manufacturing costs. The process for manufacturingnanosized Group IVA particles by methods disclosed herein are far moreeconomical than manufacturing of Group IVA nanoparticles from “atom up”methods, such as plasma enhanced chemical vapor deposition (PECVD), hotwire chemical vapor deposition (HWCVD), and ion beam deposition (IBD).

The availability of feedstock for manufacturing the Group IVA submicronparticles is plentiful and economical, as there are many sources ofsilicon and germanium derived from metallurgical grade ingots to variousrefined stage ingots. For silicon, the bulk material ranges fromamorphous to polycrystalline and crystalline. Purities range from about95% pure to 99.9999% pure. Silicon and germanium are available withdopants added that render the semiconductor properties as n-type (B, orAl) or p-type (N, P, or As). Of the refined crystalline andpolycrystalline bulk materials, wafers from ingots with specificresistivity are available for use in semiconductor microelectronicsmanufacturing and solar photovoltaic cell manufacturing. Kerf from wafermanufacturing and scrap or defective wafers are also available atrecycled material prices.

As another advantage, the ability to handle and store the Group IVAparticles disclosed herein without rigorous exclusion of air andmoisture is a distinct advantage, particularly in device manufacturing.Unlike most semiconductor devices where semiconducting films aremanufactured in situ with strict controls to exclude oxygen andmoisture, the Group IVA submicron particles disclosed herein may bemanufactured separately from the device and can be stored in drypowdered form for up to several months without decomposition.

Thus, the methods disclosed herein allow functionalization of Group IVAmaterials for any application on any substrate/carrier that wouldotherwise require heat, sintering, environmentally controlled cleanrooms and environmentally unfriendly etching, and substrates that wouldstand up to the heat processing, etc. Existing methods can be used onlyin applications or on substrates that will support the status quo heatand clean room based method to bond materials together and to thesubstrate or carrier.

As another advantage, the Group IVA particles and methods disclosedherein may be applied in technologies in such a way as to overcomeexisting problems in the art. The capability of forming formal covalentbonds to surrounding media from the passivated submicron particlesthrough low-energy reactions allows the formation of materials that haveoptimized charge mobility from the particle to the surrounding media. Assuch, the Group IVA particles have applications in lithium ion batteryand photovoltaic technologies. For example, inks manufactured from theGroup IVA particles can be applied to conductive substrates to makefully functioning lithium ion batteries having charge/dischargecapacities, charge capacity fade, and charging rates suitable forcommercial use, and optionally superior to currently availabletechnologies.

The Group IVA particles may be incorporated into a porous covalentframework to provide a composite for use in anodes of lithium ionbatteries, functioning as high capacity anodes having high chargemobility. The composite can provide optimum porosity, allowing ion flowin all directions, thereby reducing internal resistance that can lead tothe generation of heat. The composite can accommodate space requirementsfor lithium at the anode, and resist mechanical breakdown as compared toknown silicon based composites. The composite can also provide conduitsfor electrical charge mobility to and from sites where lithium ions(Li⁺) become reduced to lithium metal)(Li⁰), and the reverse process inwhich Li⁰ atoms become oxidized to Li⁺. The facile electron mobility maybe beneficial also in suppressing the formation of solid electrolyteinterface (SEI) films believed to form from solvent decomposition as aconsequence of localized electrical potentials. The composite, whichconducts charge efficiently, can provide increased recharge rate,decreasing the time required to recharge the battery.

1. DEFINITION OF TERMS

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art. In case of conflict, the present document, includingdefinitions, will control. Preferred methods and materials are describedbelow, although methods and materials similar or equivalent to thosedescribed herein can be used in practice or testing of the presentinvention. All publications, patent applications, patents and otherreferences mentioned herein are incorporated by reference in theirentirety. The materials, methods, and examples disclosed herein areillustrative only and not intended to be limiting.

As used in the specification and the appended claims, the singular forms“a,” “and” and “the” include plural references unless the contextclearly dictates otherwise. The terms “comprise(s),” “include(s),”“having,” “has,” “can,” “contain(s),” and variants thereof, as usedherein, are intended to be open-ended transitional phrases, terms, orwords that do not preclude the possibility of additional acts orstructures. The present disclosure also contemplates other embodiments“comprising,” “consisting of” and “consisting essentially of” theembodiments or elements presented herein, whether explicitly set forthor not.

2. FUNCTIONALIZED GROUP IVA PARTICLES

Disclosed herein are Group IVA particles passivated with at least onelayer of material covering at least a portion of the particle. Theparticles include at least one Group IVA element (e.g., silicon,germanium, or tin). The layer of material may be a covalently bondednon-dielectric layer of material, such as a hydrocarbon. The passivatedGroup IVA particles may also be referred to herein as “Group IVAparticles,” “functionalized Group IVA particles,” “surface-modifiedGroup IVA particles,” or a derivative term thereof.

The surface-modified Group IVA particles may be combined with one ormore additional components to provide a composition suitable for aparticular application. For example, the surface-modified Group IVAparticles may be combined with a conductive adhesion additive, a dopantadditive, other additional components, or a combination thereof.

FIG. 2 depicts a simplified representation of passivated Group IVAparticles. The Group IVA particles are shown as squares, which are meantto represent cubic particles, although the particles may have irregularshapes and may have a range of sizes. Particle 1, with a black outline,represents particles passivated with benzene, and can be prepared fromwafers ground in the absence of oxygen and/or trace amounts ofadventitious water. Particle 2 represents Group IVA particles that arepartially passivated and partially oxidized (the putative oxidizedportions of the surface are represented in light blue). The oxidizedportion is inactive and may have been present prior to comminution or itmay have been formed from the presence of oxygen and/or water during thecomminution to the micron- or submicron-sized Group IVA particles.Particle 3 represents Group IVA particles after they have beensurface-modified (e.g., with catechol, 2,3-dihydroxynaphthalene, or9,10-dibromoanthracene). A modification reaction from particle 2 toparticle 3 is shown in FIG. 3 (the modified surfaces of particle 3 arerepresented with lavender stripes). Particle 4 of FIG. 2 represents aGroup IVA particle that is fully surface-modified.

The Group IVA particles may be micron or submicron sized particles. Theparticles may have a diameter of less than 25 microns, less than 20microns, less than 15 microns, less 10 microns, less than 5 microns,less than 1 micron, less than 0.5 micron, less than 0.1 micron, or lessthan 0.05 micron. The particles may have a diameter ranging from about0.05 micron to about 25 microns, or from about 0.1 micron to about 1micron. The particles may have a diameter of 0.01 micron, 0.02 micron,0.03 micron, 0.04 micron, 0.05 micron, 0.06 micron, 0.07 micron, 0.08micron, 0.09 micron, 0.10 micron, 0.2 micron, 0.3 micron, 0.4 micron,0.5 micron, 0.6 micron, 0.7 micron, 0.8 micron, 0.9 micron, or 1 micron.The particles produced by the processes disclosed herein may produceparticles of uniform diameter, or may produce a distribution ofparticles of variable diameter.

a. Group IVA Elements and Materials

The Group IVA particles may include elemental silicon (Si), germanium(Ge) or tin (Sn), in their elemental form, or available in a wide rangeof purities. Impurities may be naturally occurring impurities that occurin metallurgical grade (MG) bulk materials, or may be intentionallyadded dopants to render the semiconducting properties of the Group IVAmaterials as n-type or p-type. For silicon, the metallurgical grade bulkmaterial may range from amorphous to polycrystalline and crystalline;and purities may range from about 95% pure to 99.9999% pure. Dopantsthat render Group IVA materials as p-type semiconductors are typicallyfrom Group IIIA elements, such as boron (B) or aluminum (Al). Dopantsthat render Group IVA semiconductors as n-type are typically from GroupVA elements, such as nitrogen (N), phosphorous (P) or arsenic (As).Naturally occurring impurities in metallurgical grade Si typicallyinclude metallic elements in the form of metal oxides, sulfides andsilicides. The major metallic elements include aluminum (Al), iron (Fe),calcium (Ca) and titanium (Ti), but other elements can be observed intrace quantities.

The Group IVA particles may be derived from a variety of feedstocks. Incertain embodiments, the Group IVA particles may be derived from wafers,such as silicon wafers. Of the refined crystalline and polycrystallinebulk materials, wafers from ingots with specific resistivity areavailable from semiconductor microelectronics manufacturing and solarphotovoltaic cell manufacturing. Kerf from wafer manufacturing andscrap, or defective wafers are also available at recycled materialprices.

b. Materials for Passivation

The Group IVA particles disclosed herein are functionalized with atleast one layer of material over at least a portion of the particle. Thelayer of material may be covalently bonded to the Group IVA particle.The layer of material may be a non-dielectric layer of material, such asa hydrocarbon. The passivated Group IVA particle may be stable tooxidation in air at room temperature.

The Group IVA particles may be passivated with a variety of compounds,also referred to as “modifiers” or “modifier reagents.” The compound maybe an organic compound, such as a hydrocarbon based organic compound. Incertain embodiments, the compound may be selected from the groupconsisting of alkenes, alkynes, aromatics, heteroaromatics,cycloalkenes, alcohols, glycols, thiols, disulfides, amines, amides,pyridines, pyrrols, furans, thiophenes, cyanates, isocyanates,isothiocyanates, ketones, carboxylic acids, amino acids, and aldehydes.In certain embodiments, the compound may be selected from the groupconsisting of toluene, benzene, a polycyclic aromatic, a fullerene, ametallofullerene, a styrene, a cyclooctatetraene, a norbornadiene, aprimary C₂-C₁₈ alkene, a primary C₂-C₁₈ alkyne, a saturated orunsaturated fatty acid, a peptide, a protein, an enzyme,2,3,6,7-tetrahydroxyanthracene, catechol, 2,3-hydroxynaphthalene,9,10-dibromoanthracene, and any combination thereof.

Hydrocarbons chosen for passivation may bear other functional groupsthat upon activation will form covalent bonds with other reagents. Thisproperty provides a basis for covalently linking the Group IVA particlesas structural units in building reticular covalent networks.Hydrocarbons chosen for passivation can vary in size and polarity. Bothsize and polarity can be exploited for targeted particle sizeselectivity by solubility limits in particular solvents. Partitioning ofparticle size distributions based on solubility limits is one tactic fornarrowing of particle size distributions in commercial scale processes.

While the possibilities of structure and function for Group IVAsubmicron particles made by the methods disclosed herein are unlimited,the following embodiments are given as examples to demonstrate the rangeof flexibility for building functional particles through low energyreactions conducted at or near room temperature.

In certain embodiments, the Group IVA particle may be passivated withtoluene.

In certain embodiments, the Group IVA particle may be passivated withbenzene. A benzene passivated Group IVA particle may serve as a stableintermediate for further modification. Benzene is one of few organichydrocarbons that will bond reversibly to silicon surfaces. Thus, abenzene passivated Group IVA material is a convenient stableintermediate for introducing other functional hydrocarbons to theparticle surface. This is one of few forms of Group IVA material inwhich thermodynamics plays an important role in the surface chemistry asopposed to be being dominated by kinetics.

In certain embodiments, the Group IVA particle may be passivated with anaromatic hydrocarbon, such as a polycyclic aromatic hydrocarbon.Aromatic hydrocarbons provide for charge mobility across the passivatedparticle surface. Hydrocarbons with extended pi systems through whichcharge can travel may be preferred in certain embodiments fornon-dielectric passivation of Group IVA material surfaces.

In certain embodiments, the Group IVA particle may be passivated with acarbon nanotube, a fullerene, or a metallofullerene. Such materials maybe applied to the particle surfaces either directly to hydrogenpassivated surfaces, or by replacement of benzene passivated surfaces.Fullerenes have a very high capacity to disperse electric charge and mayimpart properties useful in microelectronic applications.

In certain embodiments, the Group IVA particle may be passivated withstyrene. Such materials may be applied directly to hydrogen or benzenepassivated surfaces. Styrene is known to bond primarily through thependant vinyl group, leaving the aromatic ring unchanged and free tointeract with surrounding solvents, electrolytes, or to be modified byaromatic ring substitution reactions. Functional groups on the phenylring may be used as a reactive precursor for forming covalent bonds to asurrounding framework.

In certain embodiments, the Group IVA particle may be passivated withcyclooctatetraene (COT). Such a material may be applied to hydrogen orbenzene passivated surfaces, with alternating carbon atoms formallybonded to the particle surface while the other four carbon atoms notbonded directly to the particle surface are connected by two paralleldouble bonds, providing a diene site capable of Diels-Alder typereactions.

In certain embodiments, the Group IVA particle may be passivated with anorbornadiene reagent. Such materials may be applied to hydrogen orbenzene passivated surfaces with attachment of one or both double bonds.If both double bonds interact with the particle surface, a strainedstructure comparable to quadracyclane may result.Norbornadiene/quadracyclane is known to be an energy storage couple thatneeds a sensitizer (acetophenone) to capture photons. In certainembodiments, silicon or germanium may also function as a sensitizer.

In certain embodiments, the Group IVA particle may be passivated with anormal primary alkene or alkyne having 6-12 carbon chain lengths. Thealkene or alkyne can be used as the reactive medium for the purpose ofattaching hydrocarbons to the surface of the Group IVA particles toincrease particle size or to change solubility properties of theparticles. The longer alkane chain lengths may garner moreintermolecular attraction to solvents, resulting in increased solubilityof the particles. Changing the size of Group IVA particles by attachinghydrocarbons may alter photoluminescence properties.

In certain embodiments, the Group IVA particle may be passivated with abiologically active reactive media. Such materials can be used toreplace hydrogen passivated surfaces to synthesize biological markersthat respond to photons. Fatty acids may bond to active surfaces throughthe carboxylate group or through one of the chain's unsaturated bonds.Amino acids are water soluble and may bond either though the primaryamine or through the acid end, depending on pH. Similarly, peptides,proteins, enzymes all have particular biological functions that may belinked to Group IVA nanoparticle markers.

In certain embodiments, passivated Group IVA nanoparticles may reside incommunication with a porous framework capable of transmitting charge incommunication with liquid crystal media having charge conductionproperties. Such particles may be used for the purpose of capturing andselectively sequestering chemical components of a complex mixture, as amethod of measuring their relative concentrations in the mixture. Themethod of measurement may be by capture of photons by the semiconductornanoparticles and measurement of electrical impulses generated fromphotovoltaic properties of said nanoparticles or by sensingphotoluminescence as a result of reemitted photons from the media thathas been influenced by the captured chemical components.

In certain embodiments, bifunctional organic chains may be used toreplace hydrogen or benzene passivated surfaces. For example,2,3,6,7-tetrahydroxyanthracene has two hydroxyl groups at each end of afused chain of three aromatic rings. This hydrocarbon chain may be usedto build a covalent framework and may be used to link Group IVAnanoparticles to the framework. The chain length structure andfunctional groups at the ends of the chains can vary. Some functionalgroups used for cross-linking between building units can include, butare not limited to: aldehydes, carboxylates, esters, borates, amines,amides, vinyl, halides, and any other cross-linking functional groupused in polymer chemistry. Frameworks based on covalently linkedporphyrin may have extraordinarily high charge (hole conducting)mobility, greater than amorphous silicon and higher than any other knownhydrocarbon composite. Si nanoparticles linked covalently to porouscovalent frameworks may serve as high capacity electrode composites forlithium-ion batteries. FIG. 4 depicts Group IVA nanoparticlesfunctionalized with 2,3,6,7-tetrahydroxyanthracene groups.

In certain embodiments, aromatic passivating hydrocarbons may be used toreplace hydrogen bonded to reactive surfaces of the Group IVA particles.The aromatic hydrocarbons may promote high charge mobility and caninteract with other planar pi systems in the media surrounding theparticle. This embodiment may be applied to functioning solarphotovoltaic (PV) cells. The aromatic hydrocarbons that form thepassivating layer on the particle may or may not possess functionalgroups that form covalent bonds to the particle or the surroundingmedia. For example, toluene bonds to active surfaces on silicon,effectively passivating the surface and permitting electrical charge tomove from photon generated electron hole pairs in p-type crystallinesilicon particles. Sustained electrical diode properties have beenmeasured in films made with high K-dielectric solvents and both p-typeand n-type silicon particles passivated with toluene.

In certain embodiments, the Group IVA particle may be passivated withbenzene, toluene, catechol, 2,3-dihydroxynaphthalene,2,3-dihydroxyanthracene, 2,3,6,7-tetrahydroxyanthracene,9,10-dibromoanthracene, or a combination thereof. It is to be understoodthat the term “passivated,” as used herein, refers to Group IVAparticles that may be partially or fully passivated. For example, incertain embodiments, the Group IVA particle may be partially passivatedwith benzene, toluene, catechol, 2,3-dihydroxynaphthalene,2,3-dihydroxyanthracene, 2,3,6,7-tetrahydroxyanthracene,9,10-dibromoanthracene, or a combination thereof. In certainembodiments, the Group IVA particle may be fully passivated withbenzene, toluene, catechol, 2,3-dihydroxynaphthalene,2,3-dihydroxyanthracene, 2,3,6,7-tetrahydroxyanthracene,9,10-dibromoanthracene, or a combination thereof.

c. Methods of Passivation

The methods of passivation disclosed herein may be conducted at or nearroom temperature. The methods allow functionalization of Group IVAmaterials for any application on any substrate/carrier that wouldotherwise require heat, sintering, environmentally controlled cleanrooms and environmentally unfriendly etching, and substrates that wouldstand up to the heat processing, etc.

In certain embodiments, passivated Group IVA particles may be preparedby providing a first Group IVA micron or submicron sized particle; andtreating the particle with a material for passivation to provide apassivated Group IVA particle.

In certain embodiments, passivated Group IVA particles may be preparedby providing a first Group IVA micron or submicron sized particle; andtreating the first particle with a compound (preferably other thanhydrogen) to provide a passivated Group IVA particle. In certainembodiments, the compound may be benzene. In certain embodiments, thecompound may be a material for passivating the Group IVA particle byforming one or more covalent bonds therewith.

In certain embodiments, passivated Group IVA particles may be preparedby subjecting a material comprising a Group IVA element (e.g., bulkcrystalline silicon (c-Si) ingots and/or silicon powder such as 325 meshsilicon powder) to comminution in the presence of benzene and optionallyone or more non-competing solvents to provide sub-micron to nano-sizedbenzene-passivated Group IVA particles (e.g., 200-300 nm Group IVAparticles); and treating the benzene-passivated Group IVA particles witha material for passivation (e.g., 2,3-dihydroxynaphthalene), optionallyin the presence of a non-competing solvent (e.g., triglyme). Optionally,the passivated Group IVA particles may be combined with one or moreadditives (e.g., conductive adhesion additives and/or dopant additives)to provide a composition or a composite.

In certain embodiments, passivated Group IVA particles may be preparedby subjecting a material comprising a Group IVA element (e.g., bulkcrystalline silicon (c-Si) ingots and/or silicon powder such as 325 meshsilicon powder) to comminution in the presence of a material forpassivation (other than benzene or hydrogen). The comminution mayinclude use of benzene and/or a non-competing solvent (e.g., triglyme)to provide the sub-micron to nano-sized passivated Group IVA particles(e.g., 200-300 nm Group IVA particles). Optionally, the passivated GroupIVA particles may be combined with one or more additives (e.g.,conductive adhesion additives and/or dopant additives) to provide acomposition or a composite.

In certain embodiments, passivated Group IVA particles may be preparedby subjecting a material comprising a Group IVA element (e.g., bulkcrystalline silicon (c-Si) ingots and/or silicon powder such as 325 meshsilicon powder) to comminution in the presence of benzene and optionallyone or more non-competing solvents to provide sub-micron to nano-sizedbenzene-passivated Group IVA particles (e.g., 200-300 nm Group IVAparticles); isolating the benzene-passivated Group IVA particles (e.g.,by removing solvent(s) under vacuum); treating the benzene-passivatedGroup IVA particles with a modifier reagent (e.g.,2,3-dihydroxynaphthalene), optionally in the presence of a non-competingsolvent (e.g., triglyme) for a selected time (e.g., 6 hours) andtemperature (e.g., 220° C.); and isolating the modified Group IVAparticles. Optionally, the modified Group IVA particles may be combinedwith one or more conductive adhesion additives (e.g., C₆₀, C₇₀ Fullerenederivatives) and/or dopant additives (e.g., C₆₀F₄₈) in a selectedsolvent (e.g., dichloromethane) to provide a slurry; sonicated for aselected time period (e.g., 10 minutes); and optionally dried to providea composition of modified Group IVA particles and additives.

In certain embodiments, passivated Group IVA particles may be preparedby subjecting a material comprising a Group IVA element (e.g., bulkcrystalline silicon (c-Si) ingots and/or silicon powder such as 325 meshsilicon powder) to comminution in the presence of a material forpassivation (other than benzene or hydrogen) and optionally one or morenon-competing solvents and/or benzene to provide sub-micron tonano-sized passivated Group IVA particles (e.g., 200-300 nm Group IVAparticles); and isolating the passivated Group IVA particles (e.g., byremoving solvent(s) under vacuum). Optionally, the modified Group IVAparticles may be combined with one or more conductive adhesion additives(e.g., C₆₀, C₇₀ Fullerene derivatives) and/or dopant additives (e.g.,C₆₀F₄₈) in a selected solvent (e.g., dichloromethane) to provide aslurry; sonicated for a selected time period (e.g., 10 minutes); andoptionally dried to provide a composition of modified Group IVAparticles and additives.

In certain embodiments, passivated Group IVA particles may be preparedby providing a first Group IVA micron or submicron sized particle; andtreating the first particle with a compound (preferably other thanhydrogen, and optionally other than benzene) to provide a passivatedGroup IVA particle.

In certain embodiments, passivated Group IVA particles may be preparedby providing a first Group IVA micron or submicron sized particle;treating the first particle with benzene to yield a benzene passivatedGroup IVA particle; and treating the benzene passivated Group IVAparticle with a compound (preferably other than hydrogen and benzene) toprovide a passivated Group IVA particle.

In certain embodiments, passivated Group IVA particles may be preparedby providing a first Group IVA micron or submicron sized particle;treating the first particle with a protic acid to provide a hydrogenpassivated Group IVA particle; and treating the hydrogen passivatedGroup IVA particle with a compound (preferably other than hydrogen) toprovide a passivated Group IVA particle.

In certain embodiments, passivated Group IVA particles may be preparedby providing a first Group IVA micron or submicron sized particle;treating the first particle with a protic acid to provide a hydrogenpassivated Group IVA particle; treating the hydrogen passivated GroupIVA particle with benzene to yield a benzene passivated Group IVAparticle; and treating the benzene passivated Group IVA particle with acompound (preferably other than hydrogen) to provide a passivated GroupIVA particle.

In cases where it is desirable to replace benzene mono-layers withfunctional hydrocarbons other than solvents, it may be necessary to stirthe benzene passivated particles in a non-functional solvent (alsoreferred to herein as a “non-competing solvent”) with the desiredfunctional hydrocarbon dissolved or suspended in it. Exemplarynon-functional solvents useful in methods of preparing surface-modifiedGroup IVA particles include, but are not limited to, 1,2-dimethoxyethane(also referred to as glyme, monoglyme, dimethyl glycol, or dimethylcellosolve); 1-methoxy-2-(2-methoxyethoxy)ethane (also referred to asdiglyme, 2-methoxyethyl ether, di(2-methoxyethyl) ether, or diethyleneglycol dimethyl ether); 1,2-bis(2-methoxyethoxy)ethane (also referred toas triglyme, triethylene glycol dimethyl ether,2,5,8,11-tetraoxadodecane, 1,2-bis(2-methoxyethoxy)ethane, ordimethyltriglycol); 2,5,8,11,14-pentaoxapentadecane (also referred to astetraglyme, tetraethylene glycol dimethyl ether,bis[2-(2-methoxyethoxy)ethyl] ether, or dimethoxytetraglycol);dimethoxymethane (also referred to as methylal); methoxyethane (alsoreferred to as ethyl methyl ether); methyl tert-butyl ether (alsoreferred to as MTBE); diethyl ether; diisopropyl ether; di-tert-butylether; ethyl tert-butyl ether; dioxane; furan; tetrahydrofuran;2-methyltetrahydrofuran; and diphenyl ether. For example, naphthalenedissolved in triglyme replaces benzene on the surface of Group IVAparticles upon stirring at reflux temperature under nitrogen atmosphere.

The first Group IVA micron or submicron sized particle may be derivedfrom a variety of feedstocks. In certain embodiments, the firstparticles may be derived from wafers, such as silicon wafers. Of therefined crystalline and polycrystalline bulk materials, wafers fromingots with specific resistivity are available from semiconductormicroelectronics manufacturing and solar photovoltaic cellmanufacturing. Kerf from wafer manufacturing and scrap, or defectivewafers are available at recycled material prices.

The first Group IVA micron or submicron sized particle may be preparedfrom feedstocks by any suitable process. In certain embodiments, thefirst Group IVA particle may be prepared from bulk Group IVA materialsby comminution processes known in the art. Particle size rangesobtainable from comminution of bulk Group IVA materials has improvedwith the development of new milling technologies in recent years. Usingmilling techniques such as high energy ball milling (HEBM), fluidizedbed bead mills, and steam jet milling, nanoparticle size ranges may beobtained. Bulk materials are available commercially in a wide range ofspecifications with narrow ranges of measured electrical resistivity andknown dopant concentrations, and can be selected for milling. Otherembodiments can be created to produce micron- to nano-sized particlesusing n-type Group IVA wafers, or wafers with higher or lowerresistivity or bulk MG Group IVA ingot material following a similarprocedure as above.

Any protic acid may be used to provide the hydrogen passivated Group IVAparticle. In certain embodiments, the protic acid is a strong proticacid. In certain embodiments, the protic acid is selected from the groupconsisting of nitric acid (HNO₃), hydrochloric acid (HCl), hydrofluoricacid (HF), and hydrobromic acid (HBr). The protic acid may function topassivate the first Group IVA particle by leaching metal elementimpurities from the particles, which forms soluble metal chloride saltsand gaseous hydrogen (H₂), such that the remaining surface (e.g., Sisurface) from which impurities have been leached become weaklypassivated with hydrogen.

Hydrogen can then be replaced from the Group IVA particles with aselected compound. In certain embodiments, the hydrogen passivated GroupIVA particles may be treated with certain functional organic materials(e.g., hydrocarbons) that form strong covalent bonds with Group IVAelement. Examples of functional groups that form bonds with Group IVAsurfaces (e.g., Si surfaces) include, but are not limited to, alkenes,alkynes, phenyl (or any aromatic cyclic organic compounds), alcohols,glycols, thiols, disulfides, amines, amides, pyridines, pyrrols, furans,thiophenes, cyanates, isocyanates, isothiocyanates, ketones, carboxylicacids, amino acids, aldehydes, and other functional groups able to shareelectrons through pi bonds or lone pair electrons.

In certain embodiments, following the above sequence of treatments,silicon particles made from impure grades of bulk Si may have irregularshapes, but include a monolayer of hydrocarbons on Si surfaces that havebeen freshly exposed by leaching gettered impurities or by fracturingduring a milling process. Hydrocarbons can be chosen to replace hydrogenbonding to the Si surface that allow a high degree of charge mobility,thus rendering the Si surface effectively non-dielectric. Furtherreaction of the Si surface with oxygen leading to SiO₂ formation may beinhibited by the presence of the hydrocarbon monolayer. Even if areas ofthe nanoparticle surface are not completely free of dielectric oxides,charge mobility from the nanoparticle to a surrounding framework, orvice versa, may still occur through the non-dielectric passivated areason the surfaces.

In certain embodiments, passivated Group IVA particles may be preparedby providing a Group IVA powder; reducing the Group IVA powder tosubmicron particles; within a closed container treating at least aportion of the submicron particles with an aqueous liquid comprising aprotic acid; agitating the container for a time sufficient to passivatethe submicron particles therein with hydrogen; separating at least aportion of the aqueous liquid from the hydrogen passivated submicronparticles; and within a closed container treating the hydrogenpassivated submicron particles with a compound (other than hydrogen) toprovide passivated Group IVA particles.

The Group IVA powder may be provided by using a mortar and pestle tocrush a material comprising Group IVA elements (e.g., silicon wafers),and passing the crushed material through a sieve. The powder may bereduced to submicron particles using a ball mill. In an exemplaryembodiment, the powder may be reduced to submicron particles by aNetzsch Dynostar mill using 0.4-0.6 mm yttrium-stabilized zirconiabeads. Further processing to smaller average particle size (APS) may beaccomplished by using a smaller bead size. A 0.1 mm diameter bead orsmaller may allow APS reduction to less than 100 nm.

The treatment of the submicron particles with the protic acid may beconducted in the presence of an agitation device, such as a stir bar orceramic balls. The agitation of the container to passivate the particleswith hydrogen may be accomplished with a roller mill (e.g., at 60 rpmfor two hours). The container may be a screw top container. Afteragitating the container for hydrogen passivation (e.g., for two hours),the container may be allowed to stand motionless (e.g., for another twohours). The container may then be opened to release pressure and atleast a portion of the liquid phase removed. Optionally, additionalprotic acid may be added and the hydrogen passivation step repeated.After hydrogen passivation, the container may be opened to releasepressure and the liquid portion may be separated from the solids (e.g.,by decantation). In the same or different container and under agitation,the hydrogen passivated submicron particles may be treated with thecompound for passivation for a sufficient time (e.g., four to six hours)to affect passivation. The liquid phase may thereafter be removed fromthe solids (e.g., by syringe).

The solid passivated submicron particles may be dried by evaporation,optionally at reduced pressure at room temperature. Optionally,evaporation may be achieved under reduced pressure. Preferably, whenunder reduced pressure, care is taken to provide sufficient heat to theevacuated vessel to avoid freezing of the solvent(s). Preferably, careis taken to avoid sweeping nano particles into the receiving flask whenthe velocity of the solvent vapors is high.

In an industrial process, solvents may be removed by circulating drynitrogen gas across heated evaporations plates covered with a slurry ofthe particles/solvent at near atmospheric pressure. The solventsaturated gas may be passed through a condenser to recover the solventsand restore the unsaturated gas for further recirculation. This processmay minimize carryover of nanoparticles into the solvent condenser.

FIG. 5 shows one exemplary process for preparing functionalized GroupIVA particles. The Group IVA particles may be derived from bulkcrystalline silicon (c-Si) ingots (e.g., P-doped (n-type) silicon havinga resistivity of 0.4-0.6 Ωcm⁻¹), and/or silicon powder such as 325 meshsilicon powder (e.g., 325 mesh Si, 99.5% available from Alfa Aesar, 26Parkridge Rd Ward Hill, Mass. 01835 USA; or metallurgical grade c-Si 325mesh). The bulk c-Si ingots can be sliced into wafers. Wheremetallurgical c-Si 325 mesh is used, the material may be subjected toacid leaching and hydrofluoric (HF) acid etching to provide n-biased lowresistivity porous c-Si. The sliced wafers and/or the silicon powder maybe subjected to comminution in benzene to provide sub-micron tonano-sized benzene-passivated c-Si particles (e.g., 200-300 nmparticles). The initial solids loading in the comminution slurry may bebetween 30 wt % to 40 wt %, and decrease (by adding additional solvent)as the particle size distribution declines in order to maintain anoptimum slurry viscosity. The benzene solvent may be removed via vacuumdistillation followed by vacuum drying (e.g., for 6 hours at 23° C.) toprovide the benzene-passivated c-Si particles. A selected amount (e.g.,1 gram) of the benzene-passivated c-Si particles may be treated with amodifier reagent (e.g., 2,3-dihydroxynaphthalene) in a non-functionalsolvent (e.g., triglyme) and refluxed for a selected time (e.g., 6hours) and temperature (e.g., 220° C.). After refluxing, the modifiednc-Si particles may be allowed to settle and the non-functional solventremoved (e.g., by decanting, or filtering). The modified nc-Si particlesmay be washed (e.g., with an ether solvent) and then dried. The modifiednc-Si particles (e.g., optionally in a dried and powdered form) may becombined with one or more conductive adhesion additives (e.g., C₆₀, C₇₀Fullerene derivatives) in a selected solvent (e.g., dichloromethane) toprovide a slurry. Optionally, a dopant additive (e.g., C₆₀F₄₈) may alsobe added to the slurry. The slurry may be sonicated for a selected timeperiod (e.g., 10 minutes) and then dried (e.g., air dried or vacuum) toprovide a composition of modified nc-Si particles and conductive/binderadditives.

d. Characterization of Group IVA Particles

The Group IVA particles may be characterized by a variety of methods.For example, characterization of the passivated particles may beaccomplished with scanning electron microscopy (SEM), thermogravimetricanalysis—mass spectrometry (TGA-MS), and/or molecular fluorescencespectroscopy.

SEM images may be used to measure individual particles and to gain moreassurance that particle size measurements truly represent individualparticles rather than clusters of crystallites. While SEM instrumentsalso have the capability to perform Energy Dispersive X-ray Spectrometry(EDS), it is also possible with sufficiently small particle sizes thatan elemental composition will confirm the presence of carbon and theabsence of oxides through observance and absence respectively of theircharacteristic K-alpha signals. Iron and other metal impurities may beobserved and do not interfere with the observance of lighter elements.

Another analytical method that can be used to demonstrate the presenceof and identify the composition of monolayers on nanoparticles is thecombined method of thermogravimetric analysis and mass spectrometry(TGA-MS). With sufficient surface area, the fraction of surfacemolecules to the mass of the particles may be sufficiently high enoughthat mass of the monolayer can be detected gravimetrically as it desorbsor disbonds from the particle surfaces when a sample is heated. Excesssolvent evolved as the mass is heated will appear near the normalboiling point of that solvent, while solvent molecules that belong tothe bonded monolayer will be released at a significantly highertemperature. If the release of the monolayer comprises too small of afraction of the total mass weight to be seen on a percentage scale oftotal mass lost, it may still be detected by a mass-spectrometer used tomonitor off gases during a TGA experiment. Monitoring the total ioncurrent derived from the major mass fragments of the surface molecules'parent ion is a very sensitive tool to verify composition and theprecise temperature at which these molecules are released.

Still another very sensitive test to detect the presence ofsurface-bound unsaturated or aromatic hydrocarbons is by itsfluorescence spectrum. While the measurement of a fluorescence spectrumcan be accomplished by more than one method, a reflectance spectrum froma slurry or suspension of Group IVA particles in a non-fluorescingsolvent flowing in a HPLC stream through a fluorescence detector can beemployed with nanoparticles. By measuring shifts in the irradiationmaxima and the resulting fluorescence spectra of the bound monolayercompared with that of the free solvent, the perturbation due to thesurface bonding interactions can be assessed.

For nanoparticles less than about 50 nm, the use of nuclear magneticresonance (NMR) becomes a feasible method to measure the effects ofbonding of the surface molecules by observing the resonance of singletstate isotopes that have strong gyromagnetic ratios. Carbon 13,hydrogen, and silicon 29 are all candidates that exhibit reasonablesensitivity toward NMR. Because these nanoparticles may be insoluble inall solvents, a preferred technique to acquire NMR spectra in the solidstate is by the method of cross-polarization—magic angle spinning(CP-MAS) NMR spectrometry. Significant resonance shifts would beexpected from bonding interactions with surface molecules compared tothe unperturbed or natural resonance positions. These resonance shiftsmay indicate the predominant mode of bonding between specific atoms ofthe surface molecules and the surface Group IVA atoms. The presence ofany paramagnetic or ferromagnetic impurities in the Group IVA materialmay interfere with and prevent the acquisition of NMR spectra. Thus,preferably only highly pure, iron-free Group IVA particles of less than50 nm diameter are candidates for NMR analysis.

3. COMPOSITIONS AND COMPOSITES

The functionalized Group IVA particles may be provided in compositions(e.g., inks, pastes, and the like) or composites. The compositions orcomposites may include the functionalized Group IVA particles, andoptionally one or more additive components. In certain embodiments, acomposition or composite includes functionalized Group IVA particles anda conductive cohesion additive. In certain embodiments, a composition orcomposite includes functionalized Group IVA particles and a dopantadditive. In certain embodiments, a composition or composite includesfunctionalized Group IVA particles and a solvent. In certainembodiments, a composition or composite includes functionalized GroupIVA particles, a conductive cohesion additive, and a dopant additive. Incertain embodiments, a composition or composite includes functionalizedGroup IVA particles, a conductive cohesion additive, and a solvent. Incertain embodiments, a composition or composite includes functionalizedGroup IVA particles, a dopant additive, and a solvent. In certainembodiments, a composition or composite includes functionalized GroupIVA particles, a conductive cohesion additive, a dopant additive, and asolvent.

The functionalized Group IVA particles may be present in a composite inan amount ranging from 50 wt % to 100 wt %, 60 wt % to 100 wt %, or 75wt % to 100 wt %. In certain embodiments, the functionalized Group IVAparticles may be present in a composite in an amount of about 50 wt %,about 60 wt %, about 65 wt %, about 70 wt %, about 75 wt %, about 80 wt%, about 85 wt %, about 90 wt %, about 95 wt %, or about 100 wt %. Incertain embodiments, the functionalized Group IVA particles may bepresent in a composite in an amount of 50 wt %, 51 wt %, 52 wt %, 53 wt%, 54 wt %, 55 wt %, 56 wt %, 57 wt %, 58 wt %, 59 wt %, 60 wt %, 61 wt%, 62 wt %, 63 wt %, 64 wt %, 65 wt %, 66 wt %, 67 wt %, 68 wt %, 69 wt%, 70 wt %, 71 wt %, 72 wt %, 73 wt %, 74 wt %, 75 wt %, 76 wt %, 77 wt%, 78 wt %, 79 wt %, 80 wt %, 81 wt %, 82 wt %, 83 wt %, 84 wt %, 85 wt%, 86 wt %, 87 wt %, 88 wt %, 89 wt %, 90 wt %, 91 wt %, 92 wt %, 93 wt%, 94 wt %, 95 wt %, 96 wt %, 97 wt %, 98 wt %, 99 wt %, or 100 wt %.

Suitable conductive cohesion additives include, but are not limited to,C₆₀, C₇₀, and other Fullerene derivatives. In certain embodiments, theconductive cohesion additive may be C₆₀ Fullerene. The conductivecohesion additive may be present in a composite in an amount rangingfrom 0 wt % to 1 wt %, 0 wt % to 2 wt %, 0 wt % to 3 wt %, 0 wt % to 4wt %, 0 wt % to 5 wt %, 0 wt % to 10 wt %, 0 wt % to 15 wt %, 0 wt % to20 wt %, 0 wt % to 30 wt %, 0 wt % to 40 wt %, or 0 wt % to 50 wt %. Incertain embodiments, the conductive cohesion additive may be present ina composite in an amount of about 0 wt %, about 5 wt %, about 10 wt %,about 15 wt %, about 20 wt %, about 25 wt %, about 30 wt %, about 35 wt%, about 40 wt %, about 45 wt %, or about 50 wt %. In certainembodiments, the conductive cohesion additive may be present in acomposite in an amount of 0.1 wt %, 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.5 wt%, 0.6 wt %, 0.7 wt %, 0.8 wt %, 0.9 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt%, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt %, 37wt %, 38 wt %, 39 wt %, 40 wt %, 41 wt %, 42 wt %, 43 wt %, 44 wt %, 45wt %, 46 wt %, 47 wt %, 48 wt %, 49 wt %, or 50 wt %.

Suitable dopant additives include, but are not limited to, Fullerene(F)_(n), Fullerene (CF₃)_(n), polycyclic aromatic hydrocarbon (CF₃)_(n),polycyclic aromatic hydrocarbon (F_(n)). In certain embodiments, thedopant additive may be C₆₀F₄₈. The dopant additive may be present in acomposite in an amount ranging from 0 wt % to 1 wt %, 0 wt % to 2 wt %,0 wt % to 3 wt %, 0 wt % to 4 wt %, 0 wt % to 5 wt %, or 0 wt % to 10 wt%. In certain embodiments, the dopant additive may be present in acomposite in an amount of about 0 wt %, about 1 wt %, about 2 wt %,about 3 wt %, about 4 wt %, about 5 wt %, about 6 wt %, about 7 wt %,about 8 wt %, about 9 wt %, or about 10 wt %. In certain embodiments,the dopant additive may be present in a composite in an amount of 0.1 wt%, 0.2 wt %, 0.3 wt %, 0.4 wt %, 0.5 wt %, 0.6 wt %, 0.7 wt %, 0.8 wt %,0.9 wt %, 1.0 wt %, 1.1 wt %, 1.2 wt %, 1.3 wt %, 1.4 wt %, 1.5 wt %,1.6 wt %, 1.7 wt %, 1.8 wt %, 1.9 wt %, 2.0 wt %, 2.1 wt %, 2.2 wt %,2.3 wt %, 2.4 wt %, 2.5 wt %, 2.6 wt %, 2.7 wt %, 2.8 wt %, 2.9 wt %,3.0 wt %, 3.1 wt %, 3.2 wt %, 3.3 wt %, 3.4 wt %, 3.5 wt %, 3.6 wt %,3.7 wt %, 3.8 wt %, 3.9 wt %, 4.0 wt %, 4.1 wt %, 4.2 wt %, 4.3 wt %,4.4 wt %, 4.5 wt %, 4.6 wt %, 4.7 wt %, 4.8 wt %, 4.9 wt %, 5.0 wt %,5.1 wt %, 5.2 wt %, 5.3 wt %, 5.4 wt %, 5.5 wt %, 5.6 wt %, 5.7 wt %,5.8 wt %, 5.9 wt %, 6.0 wt %, 6.1 wt %, 6.2 wt %, 6.3 wt %, 6.4 wt %,6.5 wt %, 6.6 wt %, 6.7 wt %, 6.8 wt %, 6.9 wt %, 7.0 wt %, 7.1 wt %,7.2 wt %, 7.3 wt %, 7.4 wt %, 7.5 wt %, 7.6 wt %, 7.7 wt %, 7.8 wt %,7.9 wt %, 8.0 wt %, 8.1 wt %, 8.2 wt %, 8.3 wt %, 8.4 wt %, 8.5 wt %,8.6 wt %, 8.7 wt %, 8.8 wt %, 8.9 wt %, 9.0 wt %, 9.1 wt %, 9.2 wt %,9.3 wt %, 9.4 wt %, 9.5 wt %, 9.6 wt %, 9.7 wt %, 9.8 wt %, 9.9 wt %, or10.0 wt %.

Suitable solvents include, but are not limited to, dichloromethane (alsoreferred to as methylene chloride); 1,2-dichloroethane;1,1-dichloroethane; 1,1,1-trichloropropane; 1,1,2-trichloropropane;1,1,3-trichloropropane; 1,2,2-trichloropropane; 1,2,3-trichloropropane;1,2-dichlorobenzene (also referred to as ortho-dichlorobenzene);1,3-dichlorobenzene (also referred to as meta-dichlorobenzene);1,4-dichlorobenzene (also referred to as para-dichlorobenzene);1,2,3-trichlorobenzene; 1,3,5-trichlorobenzene; α,α,α-trichlorotoluene;and 2,4,5-trichlorotoluene. Suitable solvents may also include N-methylpyrrolidinone (NMP), dimethylsulfoxide (DMSO), tetrahydrofuran (THF),nitromethane, hexamethylphosphoramide (HMPA), dimethylforamide (DMF),and sulfalone. The solvent may be present in a composite in an amountranging from 0 wt % to 0.05 wt %, 0 wt % to 0.1 wt %, 0 wt % to 0.5 wt%, 0 wt % to 1 wt %, 0 wt % to 2 wt %, or 0 wt % to 3 wt %. The solventmay be present in a composite in an amount of 3 wt % or less, 2 wt % orless, 1 wt % or less, 0.5 wt % or less, 0.1 wt % or less, 0.01 wt % orless, or 0.001 wt % or less.

The solids loading (e.g., functionalized Group IVA particles, andoptional additives) in an ink (e.g., for ink jet printing) may rangefrom 1 wt % to 60 wt %, or 10 wt % to 50 wt %. In certain embodiments,the solids loading in an ink may be about 1 wt %, about 5 wt %, about 10wt %, about 15 wt %, about 20 wt %, about 25 wt %, about 30 wt %, about35 wt %, about 40 wt %, about 45 wt %, or about 50 wt %. In certainembodiments, the solids loading in an ink may be 1 wt %, 2 wt %, 3 wt %,4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt%, 13 wt %, 14 wt %, 15 wt %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt%, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt%, 29 wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt%, 37 wt %, 38 wt %, 39 wt %, 40 wt %, 41 wt %, 42 wt %, 43 wt %, 44 wt%, 45 wt %, 46 wt %, 47 wt %, 48 wt %, 49 wt %, or 50 wt %. The balanceof weight may be attributed to one or more solvents of the ink.

The solids loading (e.g., functionalized Group IVA particles, andoptional additives) in a composition (e.g., for spreading or paintbrushapplication) may range from 1 wt % to 60 wt %, 10 wt % to 50 wt %, or 25wt % to 40 wt %. In certain embodiments, the solids loading in acomposition may be about 1 wt %, about 5 wt %, about 10 wt %, about 15wt %, about 20 wt %, about 25 wt %, about 30 wt %, about 35 wt %, about40 wt %, about 45 wt %, about 50 wt %, about 55 wt %, about 60 wt %, orabout 65 wt %. In certain embodiments, the solids loading in acomposition may be 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt%, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %,16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %,24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %, 31 wt %,32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt %, 37 wt %, 38 wt %, 39 wt %,40 wt %, 41 wt %, 42 wt %, 43 wt %, 44 wt %, 45 wt %, 46 wt %, 47 wt %,48 wt %, 49 wt %, 50 wt %, 51 wt %, 52 wt %, 53 wt %, 54 wt %, 55 wt %,56 wt %, 57 wt %, 58 wt %, 59 wt %, 60 wt %, 61 wt %, 62 wt %, 63 wt %,64 wt %, or 65 wt %. The balance of weight may be attributed to one ormore solvents of the composition.

FIG. 6 shows one exemplary composite for c-Si conductive films. Thecomposite includes a plurality of silicon particles functionalized withpolycyclic aromatic hydrocarbon (PAH) compounds, which are covalentlybound to the silicon particles. The composite further comprisesFullerene or Fullerene derivatives, which may serve as electron acceptoradditives.

4. SEI FILMS

As described above, Group IVA particles may be incorporated into aporous covalent framework to provide a composite for use in anodes oflithium ion batteries, functioning as high capacity anodes having highcharge mobility. The composite can provide optimum porosity, allowingion flow in all directions, thereby reducing internal resistance thatcan lead to the generation of heat. The composite can accommodate spacerequirements for lithium at the anode, and resist mechanical breakdownas compared to known silicon based composites. The composite can alsoprovide conduits for electrical charge mobility to and from sites wherelithium ions (Li⁺) become reduced to lithium metal)(Li⁰, and the reverseprocess in which Li⁰ atoms become oxidized to Li⁺. The facile electronmobility may be beneficial also in suppressing the formation of solidelectrolyte interface (SEI) films believed to form from solventdecomposition as a consequence of localized electrical potentials. WhileSEI formation is essential for the continued operation of all secondaryLi+ batteries, too much buildup of SEI leads to high internal resistanceand capacity fade with eventual complete failure of the battery. Silicon(Si) surfaces that are not modified with an electrically conductivepassivation layer tend to form multiple SEI layers as cycling occurs dueto the delamination of the previously formed SEI layer from the Sisurface by Li⁰ expansion between the SEI and the Si surface andreformation of a new SEI layer.

The benefit of a covalently bonded conductive monolayer on the siliconsurface is that it forces the Li+ permeable SEI layer to form above theSi surface, allowing Li atoms to reside close to the Si surface withoutdelaminating the SEI layer. By selecting the optimum length, shape, andelectronic properties of the molecules that comprise the conductivemonolayer that modify the Si surface, the monolayer becomes an integralpart of the conductive framework while it also prevents the initialformation of SEI too close to the Si surface and provides space toaccommodate Li atoms. The original SEI layer stays in-tact because thecomposite as described above suppresses delamination of the original SEIlayer and the formation of additional SEI layers. The composite, whichconducts charge efficiently, can provide increased recharge rate,decreasing the time required to recharge the battery.

5. APPLICATIONS

The functionalized Group IVA particles, including compositions andcomposites comprising the functionalized Group IVA particles, may beused in a variety of applications. The Group IVA particles may be usedwhere spectral shifting due to quantum confinement is desirable, andparticle size distributions under 15 nanometers (nm) are required. TheGroup IVA particles may be used where particle size compatibility with aporous framework is desired, or it is desired to have materialproperties that resist amalgamation with other metals such as lithium(Li). The Group IVA particles may be used to provide viable commercialproducts using specific particle size distribution ranges.

The Group IVA particles may be prepared and stored for use.

The Group IVA particles may be provided into a selected solvent andapplied to a selected substrate to provide a conductive film. Thesurface-modified Group IVA particle/solvent mixture useful forapplication to a substrate may be referred to as an “ink,” a “paste,” oran “anode paste.” Suitable solvents for preparing the inks include, butare not limited to, dichloromethane (also referred to as methylenechloride); 1,2-dichloroethane; 1,1-dichloroethane;1,1,1-trichloropropane; 1,1,2-trichloropropane; 1,1,3-trichloropropane;1,2,2-trichloropropane; 1,2,3-trichloropropane; 1,2-dichlorobenzene(also referred to as ortho-dichlorobenzene); 1,3-dichlorobenzene (alsoreferred to as meta-dichlorobenzene); 1,4-dichlorobenzene (also referredto as para-dichlorobenzene); 1,2,3-trichlorobenzene;1,3,5-trichlorobenzene; α,α,α-trichlorotoluene; and2,4,5-trichlorotoluene. Substrates coated with the ink may be furtherprocessed for fabrication of products and devices including theconductive film.

Fields of useful applications for the functionalized Group IVA particlesand conductive films including the particles include, but are notlimited to, rendering solubility of functional nano particles in varioussolvent systems for the purpose of separation of particle sizedistributions; to enhance transport properties in biological systemssuch as blood or across diffusible membranes; to alter quantum effectsof nanoparticles and to optimize the properties of electronic films usedin solar photovoltaics, luminescence, biosensors, field-effecttransistors, pigments, electromagnetic energy sensitizers and catalystsinvolving electron transfers.

a. Battery Applications

The functionalized Group IVA particles may be useful in batteryapplications, particularly in anodes of lithium ion batteries. FIG. 7depicts a lithium ion battery using a anode fabricated usingfunctionalized Group IVA (e.g., a composite comprising Group IVAparticles, conductive cohesion additives, and/or dopant additives).

Anodes fabricated from the functionalized Group IVA particles mayexhibit suitable performance in one or more of specific charge capacity,fade, and discharge/recharge current, such that secondary lithium-ion(Li+) batteries containing anodes made with the surface-modified GroupIVA particles are commercially viable. The term “specific chargecapacity,” as used herein, may refer to how much energy a battery candeliver per gram of surface-modified Group IVA particles in the batteryanode. The term “fade,” as used herein, may refer to how manydischarge/recharge cycles a battery can undergo before a given loss ofcharge capacity occurs (e.g., no more than 2% over 100 cycles, or 10%over 500 cycles, or some other value determined in part by how thebattery will be used). The term “discharge/recharge current,” as usedherein, may refer to how fast a battery can be discharged and rechargedwithout sacrificing charge-capacity or resistance to fade.

Specific charge capacity, fade, and discharge/recharge current may notbe dependent on one another. In certain embodiments, a batterycomprising an anode fabricated with the surface-modified Group IVAparticles may exhibit good specific charge capacity but poor resistanceto fade. In certain embodiments, a battery comprising an anodefabricated with the surface-modified Group IVA particles may exhibit amodest specific charge capacity but very good resistance to fade. Incertain embodiments, a battery comprising an anode fabricated with thesurface-modified Group IVA particles may exhibit either good specificcharge capacity, good resistance to fade, or both, with either a good(high) discharge/recharge current or a poor (low) discharge/rechargecurrent. In certain embodiments, a battery comprising an anodefabricated with the surface-modified Group IVA particles may exhibit ahigh specific charge capacity (as close to the theoretical maximum of4,000 mAh/g as possible), excellent resistance to fade, and very fastdischarging/recharging.

Anodes prepared with unmodified, partially-oxidized particles have poorconductivity (hence low discharge/recharge current) because theparticles are only in electrical contact over a fraction of theirsurface, and they have poor specific charge capacity because some of theparticles are not in electrical contact with the majority of theparticles. This situation can be mitigated to some extent when the GroupIVA are modified (e.g., with 2,3-dihydroxynaphthalene) before they aremade into anodes. FIGS. 8-10 depict a simplified representation ofplurality of passivated Group IVA particles in electrical contact in ananode. An anode material according to FIG. 8 may provide batteries withpoor specific charge capacity but good resistance to fade. FIG. 9 showsan anode of surface-modified Group IVA particles in the presence of aC₆₀ conductive adhesion additive (the C₆₀ molecules are dark-blueVercro-like circles). When C₆₀ is added to the anode paste before makingthe anode, the density of the anode per unit volume increases, thespecific-charge capacity of the anode increases, and in some cases thedischarge/recharge current increases. The C₆₀ molecules may “glue” theparticles together, increasing the fraction of particles in electricalcontact and increasing the electrical conductivity (and hence increasingthe speed at which Li⁺ ions are initially charged into, are dischargedout of, or are recharged into, the anode). When an additional dopantadditive C₆₀F₄₈ is present (not shown in FIG. 9), one or more ofspecific charge capacity, fade, and discharge/recharge current may beimproved. FIG. 10 shows an anode fabricated from an anode pastecomprising un-oxidized functionalized Group IVA particles, a conductiveadhesion additive, and a dopant additive. The anode of FIG. 10 mayexhibit superior performance in all of specific charge capacity, fade,and discharge/recharge current.

In certain embodiments, the passivated Group IVA particles may becovalently bonded to a porous covalent framework. The frameworkincluding the Group IVA particles may be particularly useful in lithiumion battery applications. The framework may be a covalent organicframework, a metal organic framework, or a zeolitic imidazolateframework. The framework may be a 2-dimensional framework or a3-dimensional framework. A complete framework composite may comprisemultiple sheets of frameworks stacked and aligned on top of one another.The sheets may be aligned and stacked in close proximity with oneanother to provide electron mobility in the perpendicular direction tothe plane of the sheets. FIG. 11 depicts one porous framework compositeaccording to the present invention that may serve as an anode in alithium ion battery application.

Submicron silicon particles bonded to a porous covalent framework withhigh charge mobility may provide a high capacity anode in lithium-ionbatteries. Silicon is known to form amalgams with lithium having thecapacity to attract a greater mass of lithium than any other knownelement. Anodes with silicon have the capacity to attract more than 10times the mass of lithium than conventional carbon-based anodecomposites. Consequently, material scientists and battery manufacturershave attempted to form silicon bearing composites that function as theanode in lithium-ion batteries. The primary hurdle facing these effortsrelates the charge/recharge cycle stability of the anode composites.This is because no structural form of bulk silicon (or germanium) canaccommodate the spatial requirement imposed by the accumulated lithiumand the composites degrade mechanically after the first charge cycle.

Because lithium-ion batteries are often developed as secondary batteries(rechargeable) they must undergo many charge/recharge cycles (1000 ormore) without significant loss of charge capacity. Thus, if silicon isused in lithium-ion battery anodes, the structure of the composite mustbe capable of accommodating large amounts of lithium (approximately 4times the volume with a full Li charge compared to the composite with noLi accumulation). Si particles must also be small enough to resistamalgamation by lithium. Si nanowires and nanoporous silicon and quantumdots have all demonstrated the ability to attract lithium withoutcausing mechanical changes to the silicon particles. Thus, a nano-porouscomposite comprising surface-modified crystalline silicon particles maybe produced to provide porosity and high surface area that allows accessto lithium ions and space in between particles for expansion for thegrowth of reduced lithium metal.

A framework that supports silicon particles may allow Li⁺ ions tomigrate. The porous framework may accommodate solvents and electrolytesand allow free migration of ions ideally in all directions. Theframeworks can be designed with optimum porosity (see Example 1). Thereticular pattern with which the structural units are assembled mayresult in perfectly even porosity throughout the framework, allowing ionflow in all directions with no “hot spots” or areas of restricted flowthat contribute to a battery's internal resistance leading to thegeneration of heat (see Example 2). A framework may be constructed fromefficient packing of particles of random shapes within a sizedistribution that provides adequate porosity for permeation of Li⁺ ionsand electrolyte solutions.

Porous electrode composites may allow charge to be conducted from siteswhere reduction and oxidation occurs to the current collector. Theconduction path is bidirectional since the direction of charge andelectrolyte flow are reversed when the battery is being recharged asopposed to when the battery is providing electrical power. Frameworksusing planar porphyrin structural units or other conductive structuralunits within appropriate geometric shapes (i.e, Fullerenes or polycyclicaromatic hydrocarbons (PACs)) have the ability to accommodate electricalcharge in its extended pi system and the alignment of the structuralunits by the reticular assembly provides an efficient path for electronsas demonstrated by charge mobility measurements. While some electrodedesigns require the inclusion of conductive carbon in the composite, theelectrode with conductive frameworks may or may not. For example, thefunctional cells may use no added conductive carbon-based Fullerenes orPAHs other than by passivating monolayer bonded to and modifying thecrystalline particle surface.

While many conductive frameworks could be constructed, examples oforganic boronic ester frameworks are of particular interest becausetheir syntheses can be accomplished using mild non-toxic reagents andconditions and because they have interesting fire-retardant properties.Covalent Organic Frameworks (COFs) that incorporate either trisboronic-or tetraboronicester vertices bound by aromatic struts builds layeredtwo-dimensional or three-dimensional frameworks, respectively. Twoaromatic precursors, 1,2,4,5-tetrahydroxybenzene and2,3,6,7-tetrahydroxyanthracene have been described and have beencombined with boronic acids, building COFs that have very high electronmobility and remarkably good fire suppression properties. IncorporatingGroup IVA particles functionalized with these symmetric tetraolsprovides a means of covalently bonding the Group IVA particles to theCOF matrix. Functionalization of benzene passivated Group IVA particleswith either of these symmetric tetraols can be accomplished by refluxingthe benzene functionalized Group IVA particles suspended with thetetraol in benzene or in a non-competing solvent such as tryglyme. Whilebenzene can leave the particle surface without decomposition, thetetraol forms a chelate and once bonded to the particle surface will notleave.

While Group IVA particles covalently bonded to a conductive organicframework could make a novel composite for lithium battery anodes, afunctionalized Group IVA particle incorporated in layered graphite,stacked carbon nanotubes, Fullerenes, activated carbon or other lessstructured porous carbon or polymer composites could also significantlyenhance the properties of those materials toward lithium storage orother properties outlined above. In other words, the incorporation offunctionalized Group IVA particles does not necessarily have to beformally bonded into a coherent framework to realize benefits in thecomposites. In these applications, the choice of dopants that render“n-type” (nitrogen, phosphorous, antimony) and “p-type” (boron) would bechosen to populate the conduction band or depopulate the valence bandrespectively of these Group IVA semiconductors with electrons. While then-type configuration would behave more like a conductor, the p-typeconfiguration would be prone to capturing photon energy and convertingit to charged particles. Furthermore, incorporation of photo-activesemiconductors capable of capturing and transferring photon energy toelectrical charge could be useful when combined with porous electricallyactive materials that bear functional groups capable of producingunstable radicals. These radicals are known to catalyze chemicaltransformations, particularly the oxidation of stable hydrocarbons andthe oxidation of stable metals in low valence states to higher valencestates. Such activity could be useful for treatment of chemical waste,water and air purification and the capture of toxic metals such asarsenic, selenium, lead and mercury.

FIG. 12 depicts one exemplary process for preparing a battery comprisingthe functionalized Group IVA particles. The Group IVA particles may bederived from bulk crystalline silicon (c-Si) ingots (e.g., P-doped(n-type) silicon having a resistivity of 0.4-0.6 Ωcm⁻¹), and/or siliconpowder such as 325 mesh silicon powder (e.g., 325 mesh Si, 99.5%available from Alfa Aesar, 26 Parkridge Rd Ward Hill, Mass. 01835 USA;or metallurgical grade c-Si 325 mesh). The bulk c-Si ingots can besliced into wafers and surface orientation can be selected and theprecise resistivity of individual wafers can be measured and selectedprior to comminution. Where metallurgical c-Si 325 mesh is used, thematerial may be subjected to acid leaching and hydrofluoric (HF) acidetching to provide n-biased low resistivity porous c-Si. The slicedwafers and/or the silicon powder may be subjected to comminution inbenzene to provide sub-micron to nano-sized benzene-passivated c-Siparticles (e.g., 200-300 nm particles). The benzene solvent may beremoved via vacuum distillation followed by vacuum drying (e.g., 6 hoursat 23° C.) to provide the benzene-passivated c-Si particles. A selectedamount (e.g., 1 gram) of the benzene-passivated c-Si particles may betreated with a modifier reagent (e.g., 2,3-dihydroxynaphthalene) in anon-functional solvent (e.g., triglyme) and refluxed for a selected time(e.g., 6 hours) and temperature (e.g., 220° C.). After refluxing, themodified nc-Si particles may be allowed to settle and the non-functionalsolvent removed (e.g., by decanting, or filtering). The modified nc-Siparticles may be washed with an ether solvent and then dried. Themodified nc-Si particles (e.g., in a dried and powdered form) may becombined with one or more conductive adhesion additives (e.g., C₆₀, C₇₀,Fullerene derivatives) in a selected solvent (e.g., dichloromethane) toprovide a slurry. Optionally, a dopant additive (e.g., C₆₀F₄₈) may alsobe added to the slurry. The slurry may be sonicated for a selected timeperiod (e.g., 10 minutes) and then dried (e.g., air dried or vacuum) toprovide the modified nc-Si particles with conductive/binder additives.

The modified nc-Si particles with the conductive/binder additives may becombined with a selected solvent (e.g., a chlorinated solvent such astrichloropropane) to provide a conductive ink (e.g., 40-50 wt % solidsloading). The conductive ink may be applied (e.g., paintbrushapplication, film spreader) to a selected substrate (e.g., a coppersubstrate, with or without a carbon coating) and thereafter dried undera selected atmosphere (e.g., air) and temperature (e.g., 90° C.). FIG.13 depicts an exemplary copper substrate to which the conductive ink wasapplied. The ink-coated substrate may then be die-cut to discs (e.g., 16millimeter discs) using a die cutter such as that depicted in FIG. 14.The discs may then be dried under a vacuum for a selected time period(e.g. 2 hours) at a selected temperature (e.g., 100° C.).

A disc anode comprising functionalized Group IVA particles was preparedphotographed on a black metallic background with a Nikon digital cameraand at 40× and 100× power with a AmScope 40×-2000× trinocular compoundmicroscope equipped with a AmScope MA-1000 digital camera. The anode wasprepared using 99.5% pure intrinsic silicon surface modified with2,3-dihydroxynaphthalene with 10% C₆₀ conductive adhesion additive mixedin by slurrying with sonication in dichloromethane. The photographs areshown below in FIGS. 15a -15 c.

The discs, along with other components for preparing a coin cell battery(e.g., cathode, separator, electrolyte), may be assembled into a coincell under an inert atmosphere (e.g., in a glove box). FIG. 16 depicts acontrolled atmosphere glovebox with coin cell assembling equipment,including a hydraulic crimper for crimping 2032 coin cells. The coincells may include a stainless steel container that includes a polymer toseal the top and bottom and sides of the cell from each other.

b. Photovoltaic Applications

The functionalized Group IVA particles may be useful in photovoltaicapplications. The Group IVA particles may be used to provide asemiconductor film comprised of submicron Group IVA particles dispersedand in communication with an electrically-conductive fluid matrix orliquid crystal. The film may be prepared by making a semiconductorparticle suspension, depositing the semiconductor particle suspension ona substrate, and curing the semiconductor particle suspension at atemperature of 200° C. or less to form the semiconductor film. Thesemiconductor particles may be comprised of elements from the groupconsisting of B, Al, Ga, In, Si, Ge, Sn, N, P, As, Sb, O, S, Te, Se, F,Cl, Br, I, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh,Ir, Ni, Pd, Pt, Ag, Cu, Au, Zn, Cd, lanthanides, and actinides. Thesemiconductor particles may be p-type or n-type. The method may beperformed completely at room temperature.

The semiconductor films that may be applied in sequence on a substrate,rigid or flexible, may be integral parts of a functioning semiconductordevice having been assembled monolithically with no annealing during anypart of the manufacturing process. The semiconductor films may beapplied as inks printed on the substrate by ink-jet or any knownprinting process capable of creating uniform films on a substratesurface. Conductive circuitry may also be printed in the same manner asthe semiconductor films, all becoming integral parts of the completeelectronic device.

For example, in the case where the semiconductor device is aphotovoltaic cell, a p-type semiconductor film (abbreviated as “p-film”)may be applied by ink-jet to the substrate with a conductive surface.Upon sufficient curing of the p-film, an n-type semiconductor film(n-film) may be applied directly on the partially cured p-film. Afterthe first two films are sufficiently cured, conductive circuitry may beapplied on top of the n-film. The conductive circuitry can be printedthrough a mask or by such print jet capable of making narrow, wire-likeconduction pathways. The conductive circuitry on top may minimize thearea that shades incident light on the surface of the semiconductorfilms. The conductive circuitry on top of the n-film may be connected tothe negative terminal (anode), while the conductive surface under thep-film and on the substrate may be connected to the positive terminal(cathode). The cell may then be hermetically sealed with asunlight-transparent covering, gaskets and cement. A schematic diagramof such a cell is depicted in FIG. 17.

Also disclosed herein is a method of making a photovoltaic cell at roomtemperature from semiconductor films composed of Group IVA submicronparticles. In certain embodiments, photovoltaic activity may be observedin cells made by the methods in this invention using crystalline siliconfilms having a mean particle size distribution above 1 micron. Yet inother embodiments, higher photovoltaic efficiency may be achieved fromfilms made with nanoparticle size distributions such that quantumconfinement becomes an important factor in the absorption of photons andphoton-electron transitions. Distinct advantages are gained with the useof nanoparticle films in solar PV collectors, one being the efficiencyand breadth of the solar radiation spectrum that can be absorbed andconverted to electrical energy using crystalline silicon. For example,solar cells made from bulk silicon wafers are typically 30 thousandths(˜0.7 mm) thick, while some silicon nanoparticle thin films that haveequivalent photon absorption capacity need only be less than 100 nm.

Bulk crystalline silicon is inherently an indirect band gapsemiconductor, which explains why photon absorption efficiency is loweven though the natural band gap for silicon is nearly perfectlycentered in the solar spectrum. For absorption and conversion of aphoton to an electron hole pair to occur in indirect band gapsemiconductors (p-type), the conversion must be accompanied with theproduction of a phonon (a smaller packet of thermal energy). Not only issome energy lost in each conversion of photon to electron, but theseconversions do not readily occur because it is a forbidden transition.Still, forbidden transitions can and do occur, but they happen much lessfrequently than in direct band-gap semiconductors. Similarly,florescence (resulting in the annihilation of an electron or electronhole pair with the emission of a photon) also is forbidden in indirectband-gap semiconductors and allowed in direct band-gap semiconductors.Consequently, silicon is a poor luminescence semiconductor, but it iscapable of preserving energy in the form of an electron hole pair forlong enough to allow the charge to migrate to the p-n junction where itmeets an electron from the conduction band of the n-semiconductor layer.

Under ideal conditions the maximum theoretical photovoltaic efficiencyof bulk crystalline silicon is just over 30%, while in practice the bestphotovoltaic efficiency in crystalline silicon wafer solar cells is22-24%. Still, crystalline silicon wafer technology is most commonlyused in commercial solar PV panels because their efficiency is farbetter than amorphous silicon films and the PV efficiency fade over timeis very low compared to other solar PV technologies. PV efficiency forsilicon nanoparticle films has been measured in the laboratory as highas 40-50% with some expectations that even higher efficiencies areattainable. However, these devices have not yet been commercializedpresumably because the cost of commercialization is too high to competewith existing technologies.

While others have used expensive heat processing methods to fuse variouselements of the semiconductor materials to form functioningsemiconductor devices, disclosed herein is a method of making thesedevices function through the formation of formal covalent bonds and pioverlapping interactions in liquid crystal and covalent frameworkstructures through low temperature reactions. The overlying benefit fromthis approach is to lower the cost of manufacturing superior performingdevices. This is especially important for solar PV manufacturing wherethe Levelized Cost of Energy (LCOE) must decline for solar power toapproach parity with other sources of electrical energy.

Also disclosed herein is a method of applying passivated Group IVAsemiconductor particles suspended with an electrically conductive fluid.The semiconductor particles and the constituents of the liquid crystalor electrically conducting fluid or framework may be suspended in ahigh-K dielectric solvent to form a liquid ink with the appropriateviscosity suitable for the method of application. For jet printing,viscosities in the range of 10 centipoise (cp) to 30 cp may be suitable,while for gravure printing may require viscosities over 100 cp. High Ksolvents are used to promote the dispersion of nanoparticles and preventparticle agglomeration. Films may require a period of curing to allowthe alignment and or self assembly of the fluid matrix or structuralunits of the framework and to establish electrical communication withthe semiconductor particles. The curing process may involve complete orpartial evaporation of one or more components of solvent used in makingthe inks.

Solvents used in making submicron semiconductor inks may include, butare not limited to, N-methyl pyrrolidinone (NMP), dimethylsulfoxide(DMSO), tetrahydrofuran (THF), nitromethane, hexamethylphosphoramide(HMPA), dimethylforamide (DMF), and sulfalone. Many organic-basedcompounds are available that form columnar discotic liquid crystals.Examples of these include a class of compounds derived fromtriphenylene-base compounds that align with each other in stackedcolumns by hydrogen bonding. Similarly, other symmetric and asymmetricpolyaromatic hydrocarbons with planar pi systems and ring substituentsthat participate in their alignment into stack columns may be used for adiscotic liquid crystal matrix. Porphyrin based compounds may be used toform stacked arrays that can be classified with liquid crystals, or withappropriate functional groups may form covalent organic frameworks thatallow high charge mobility in their frameworks. Some combination of oneor more of the above solvents and organic-based liquid crystal orconductive framework structural units may be used for the semiconductorfilm matrixes.

c. Pollutant Capture

The functionalized Group IVA particles, as well as functionalized andnon-functionalized transition metals (e.g., copper), may be useful inthe capture of pollutants, and in particular, pollutants from combustionprocesses. Emission of mercury, for example, from combustion gas sourcessuch as coal-fired and oil-fired boilers has become a majorenvironmental concern. Mercury (Hg) is a potent neurotoxin that canaffect human health at very low concentrations. The largest source ofmercury emission in the United States is coal-fired electric powerplants. Coal-fired power plants account for between one-third andone-half of total mercury emissions in the United States. Mercury isfound predominantly in the vapor-phase in coal-fired boiler flue gas.Mercury can also be bound to fly ash in the flue gas.

Mercury and other pollutants can be captured and removed from a flue gasstream by injection of a sorbent into the exhaust stream with subsequentcollection in a particulate matter control device such as anelectrostatic precipitator or a fabric filter. Adsorptive capture of Hgfrom flue gas is a complex process that involves many variables. Thesevariables include the temperature and composition of the flue gas, theconcentration and speciation of Hg in the exhaust stream, residencetime, and the physical and chemical characteristics of the sorbent.

Currently, the most commonly used method for mercury emission reductionis the injection of powdered activated carbon (PAC) into the flue streamof coal-fired and oil-fired plants. However, despite availabletechnologies, there is an ongoing need to provide improved pollutioncontrol sorbents and methods for their manufacture.

Aspects of the invention include compositions, methods of manufacture,and systems and methods for removal of heavy metals and other pollutantsfrom gas streams. In particular, the compositions and systems are usefulfor, but not limited to, the removal of mercury from flue gas streamsgenerated by the combustion of coal. One aspect of the present inventionrelates to a sorbent comprising a Group IVA functionalized particle asdescribed herein, and/or a functionalized or non-functionalizedtransition metal (e.g., copper).

In certain embodiments, a method of removing pollutants (e.g., mercury)from a combustion flue gas stream includes injecting into the flue gasstream a sorbent comprising a functionalized Group IVA particle asdescribed herein, and/or a functionalized or non-functionalizedtransition metal (e.g., copper). The sorbent can be used and maintainfunctionality under a variety of conditions, including conditionstypical of flue gas streams found in combustion processes. In certainembodiments, the sorbent can be provided into a flue gas or processhaving a temperature of 200° F. to 2100° F., or 400° F. to 1100° F. Incertain embodiments, the sorbent can be provided into a flue gas orprocess having a temperature of 50° F. or greater, 100° F. or greater,200° F. or greater, 300° F. or greater, 400° F. or greater, 500° F. orgreater, 600° F. or greater, 700° F. or greater, 800° F. or greater,900° F. or greater, 1000° F. or greater, 1100° F. or greater, 1200° F.or greater, 1300° F. or greater, 1400° F. or greater, 1500° F. orgreater, 1600° F. or greater, 1700° F. or greater, 1800° F. or greater,1900° F. or greater, 2000° F. or greater, or 2100° F. or greater.Optionally, the injected sorbent may be collected downstream of theinjection point in a solids collection device. Optionally, the injectedsorbent can be recycled for repeat use.

In certain embodiments, the Group IVA particles described herein, and/orfunctionalized or non-functionalized transition metals (e.g., copper),can be used to provide improved capture of mercury at electrostaticprecipitators (ESPs). The majority of coal plants now have electrostaticprecipitators. The Group IVA particles described herein, and/orfunctionalized or non-functionalized transition metals (e.g., copper),may be introduced into a scrubbing process before, after, or on the ESPhighly charged plates. The captured mercury may then stay on the platesor fall into the fly ash as oxidized. Given the transfer of the energy,hydroxyl radicals may be formed and oxidation of the Hg occurs. Inparticular, the Group IV particles described herein, and/orfunctionalized or non-functionalized transition metals (e.g., copper),can be used as photo sensitizers for mercury removal. The photosensitizers can be combined with activated carbon to remove Hg.

d. Other Applications

Other applications for functionalized Group IVA particles includebiosensors, thermoelectric films, and other semiconductor devices.

6. EXAMPLES

The foregoing may be better understood by reference to the followingexamples, which are presented for purposes of illustration and are notintended to limit the scope of the invention.

Example 1 Toluene Passivated Silicon Particles

In one example, p-type silicon wafers with measured resistivity of 2-4ohm/cm² were crushed, then ground with mortar and pestle, then passedthrough a #60 mesh sieve. The powder was further reduced to submicronparticles with a ball mill. In 40 gram batches, the submicron siliconpowder was added to a 250 mL polypropylene container with 100 mL ofmuriatic acid and 4-8 ceramic balls (12 mm dia.). The screw-top lid wasclosed and the container was turned on a rolling mill at 60 rpm for twohours. Pressure buildup in the container caused the container to bulge.In some instances where larger quantities or lower grades of siliconwere treated, the container was subject to bursting due to the buildupof H₂ gas. After two hours of agitation on the roller mill, the bottlewas allowed to stand for another two hours motionless. The bottle wascarefully opened with the release of pressure and the liquid was drawnfrom the container above the solid in the bottle via syringe. Another100 mL of fresh muriatic acid was added and the bottle closed and rolledfor another 2-hour period followed by a 2-4 hour period of standing inan upright position. The bottle was opened again with release of muchless pressure than after the initial acid treatment. The aqueous liquidportion was carefully drawn from the solid as before. The decantedliquid was noticeably clearer than the liquid drawn from the first acidtreatment. After thoroughly decanting the aqueous liquid, 100 mL oftoluene was added to the solid, the screw-top lid was replaced and thebottle was rolled again for 4-6 hours with the ceramic balls remainingin the container for agitation. After allowing at least 1 hour forsettling, the lid was opened with little to no pressure released fromthe vessel and liquid was drawn away followed by another 100 mL portionof toluene added to the vessel. The vessel was again rolled to agitatethe silicon powder in toluene for another 4-6 hours before allowing themixture to settle and opening the vessel to remove the liquid toluenevia syringe. The remaining toluene was removed by evaporation assistedby reduced pressure at room temperature.

Following a similar procedure, other hydrocarbon passivated micron- tonanosized particles can be created using n-type Group IVA wafers, orwafers with higher or lower resistivity or bulk MG Group IVA ingotmaterial. The amounts of material treated can vary depending on thegrade of the bulk material and size and burst strength of polypropyleneor polyethylene container used.

Example 2 Benzene Passivated Silicon Particles

(i) In another example, following the identical milling proceduredescribe of Example 1, benzene (C₆H₆) was instead used as thepassivating hydrocarbon in place of toluene. Applied similarly, benzenemay be replaced in subsequent reactions by other hydrocarbons with morestrongly bonding functional groups. Benzene is one of few organichydrocarbons that will bond reversibly to silicon surfaces. Thus,benzene passivated Group IVA material is a convenient stableintermediate to use for introducing other functional hydrocarbons on tothe particle surface. This is one of few forms of Group IVA material inwhich thermodynamics plays an important role in the surface chemistry asopposed to be being dominated by kinetics.

(ii) In another example, wafers of three different types of silicon wereground to specification. Benzene was the solvent used during thegrinding process, but oxygen and trace amounts of water were notexcluded. The three types of silicon were (i) phosphorus-doped silicon(i.e., n-type silicon) with a manufacturer-specified resistivity of0.4-0.6 Ωcm⁻²,

(ii) boron-doped silicon (i.e., p-type silicon) with amanufacturer-specified resistivity of 0.014-0.017 Ωcm⁻², and (iii) 99.5%pure intrinsic silicon. The average particle size (APS) of the ground,benzene-coated n-type silicon particles, measured by electronmicroscopy, was found to be less than 400 nm (<400 nm).

Example 3 Passivated Silicon Particles

In another example, 325 mesh Si powder was processed by a NetzschDynostar mill using 0.4-0.6 mm yttrium-stabilized zirconia beads inbenzene. The solids loading of the Si-benzene slurry was 30-40 percent.Particle size distribution (PSD) analysis indicated that the averageparticle size (APS) was reduced to about 200 nm. Further processing tosmaller APS required a change in grinding media to smaller bead size.Changing to 0.1 mm diameter beads or smaller will allow APS reduction toless than 100 nm. Below 100 nm, further APS reduction in benzene becomesdifficult due to rapidly increasing viscosity of the slurry.Furthermore, following the APS reduction progress by light-scatteringPSDA methods becomes difficult due to particle agglomeration.

Removal of benzene from submicron particles was accomplished byevaporation of benzene under reduced pressure. Care must be taken toprovide heat to the vessel with the slurry to avoid freezing of thebenzene. A 20 mm glass tube mated between the flask containing theSi/benzene slurry and a receiving flask for the solvent condensate by24/40 ground glass joints allowed the solvent to be removed from thenano-silicon/benzene slurry. While pressure in the joined flasks wasbriefly, but repeatedly reduced via vacuum, care was taken not to applytoo much dynamic vacuum as solvent vapors easily sweep nano particlesinto the receiving flask when the velocity of those vapors is high.

On a small laboratory scale, this method is adequate for isolation ofthe Group IVA particles from solvent slurries. In an industrial process,it may be more efficient to remove solvents by circulating dry nitrogengas across heated evaporations plates covered with the slurry at nearatmospheric pressure. The solvent saturated gas may be passed through acondenser to recover the solvents and restore the unsaturated gas forfurther recirculation. This process may minimize carryover ofnanoparticles into the solvent condenser.

Characterization of the benzene passivated Si particles includes SEM,TGA-MS, and molecular fluorescence spectroscopy. SEM images were used tomeasure individual particles and to gain more assurance that particlesize measurements truly represent individual particles rather thanclusters of crystallites. While SEM instruments also have the capabilityto perform Energy Dispersive X-ray Spectrometry (EDS), it is alsopossible with sufficiently small particle sizes that an elementalcomposition will confirm the presence of carbon and the absence ofoxides through observance and absence respectively of theircharacteristic K-alpha signals. FIG. 18 is an EDS spectrum showingresolved K-alpha signals that include Si, O, and C. Iron and other metalimpurities could also be observed and do not interfere with theobservance of lighter elements.

Average Particle Size (APS):

APS as determined by a Microtrac particle size was between 200 and 300nm. Initial SEM images were recorded in addition to EDXA scans. Whilethe initial SEM images were inadequate to resolve the particle size ofthe analyzed sample, the EDXA scan revealed good data that confirms thepresence of hydrocarbon and minor oxidation (See FIGS. 20 and 19respectively). The sample was mounted on an aluminum stub, so the signalin the position of Al K-alpha seen in the EDXA scan is most likely acontribution of the Al mounting stub. The image in FIG. 20 indicatesthat the APS is well below submicron range.

Identification of Surface Organics:

One qualitative test for surface organics is the measurement of aFourier Transform InfraRed (FTIR) spectrum. FTIR measures modes ofmolecular vibrations due to stretching and bending frequencies ofmolecular bonds. While it is possible in FIG. 21 to see evidence of theFTIR fingerprint left behind by benzene, there are no significant shiftsin the C—H stretching frequencies due to perturbations from theirbonding interactions to the Si surfaces. C—C bending patterns will haveto be examined in more detail. This is where perturbations (wave numbershifts) will be most prominent if those interactions are indeed strongenough to shift bands beyond spectral resolution limits (±4 cm⁻¹).

Further evidence that benzene is bound to the particle surfaces withbonding interactions that appear stronger than hydrogen bonding, but notas well defined as would be expected from a discrete monolayer, is shownin TGA scans. FIGS. 22a and 22b are TGA scans run at heating rates of 30degrees C./s and 10 degrees C./s respectively. The initial scan at 30degrees C./s was done to quickly observe the thermal profile up to 500°C. (932° F.). In this scenario, the compound is stable to oxidation upto 500° C. (932° F.) and also notable is the fact that it appears tolose mass gradually. The solvent hangs on well past its boiling point.The slower scan rate in FIG. 22b demonstrates that while benzene iscontinuously evolved from the sample, throughout the temperature range,the material will survive up to 250° C. for several minutes beforebeginning to oxidize at this slower scan rate. For this reason, usingthis material in a fixed (packed) bed reactor held at a sustainedtemperature may not survive beyond 250° C. (482° F.). However, thedynamic desorption of surface bound benzene does not occur instantly andcould protect the Si surface from oxidation briefly at highertemperatures. The mass loss accounts for only 0.02% of the total massbefore oxidation begins to occur.

Example 4 Toluene Passivated Silicon Particles

Si particles processed in benzene solvent by milling 325 mesh intrinsicSi (99.99%, Alpha Aesar) with 0.4-0.6 mm yttrium-stabilized beads untilreaching about 300 nm apparent APS were passivated by stirring intoluene and heating to reflux under inert atmospheres. To 20 g of thedried particles in a 200 mL round bottom flask was added 50 mL oftoluene freshly distilled from sodium. The same procedure was followedwith particles made from the previous stock, but further milled with 0.1mm beads to an apparent APS less than 200 nm. The true APS estimatedfrom SEM images was less than 100 nm. In both cases, the particles wererefluxed for 1-2 hours in toluene blanketed under 1 atmosphere ofpurified nitrogen.

With toluene passivated nc-Si, a sharper decline of the mass loss isexpected in the TGA with greater sustained stability at highertemperatures. This would be expected for a passivating layercharacterized by stronger, more defined bonding interactions tolocalized sites. Due to toluene's asymmetry, stronger Si—C bondinginteractions will be formed to the ring carbon bound to methyl comparedwith other C—H ring carbon-silicon interactions. Greater evidence of C—Cbond vibrations will also be manifest in the IR spectrum band shifts.

Example 5 Lithium-Ion Coin Cells

Surfaced-modified Group IVA particles were prepared as described hereinand used to fabricate anodes, which were subsequently incorporated intolithium-ion coin cells. In general, the surface-modified Group IVAparticles were prepared, incorporated into an anode paste or ink, andapplied to a copper substrate, which was then fashioned into an anodeand incorporated into a coin cell. In certain instances, thesurface-modified Group IVA particles were combined with one or moreadditional components in the anode paste or ink (e.g., conductiveadhesion additive, a dopant additive) before application to the coppersubstrate.

Exemplary lithium-ion coin cells fabricated, along with component andfabrication variables are provided in the tables below. Several cellswere cycled for sufficient time to provide meaningful performance dataregarding charge capacity, discharge capacity, specific charge capacityand capacity fade. Charge/discharge cycles were measured on Li⁺ coincells made from the anode films combined with selected commercialcathode films and electrolytes. Cathodes were made from LiCoO₂ on an Alsubstrate, and the electrolyte was LiPF₆ in a blend of organocarbonatesolvents. A series of anodes were compared with a single selection ofcathode and electrolyte formulation.

The “capacities” for the coin cells refer to charge capacities. However,discharge capacity is also an important parameter because it representsthe amount of electrical charge that can be delivered by the coin cellwhen it has been charged according to a given set of parameters. Chargecapacity, which is measured for a given coin cell and is given in unitsof mAh (milliampere hours) is distinct from specific charge capacity,which is determined for a given anode if the anode was weighed and theweight (mass) of the copper substrate was known and can be subtracted,leaving the net weight (mass) of the anode material deposited on thatparticular anode. The specific charge capacity is then calculated bydividing the coin cell charge capacity by the mass of anode material,and this quantity is therefore given in mAh g⁻¹ (milliampere hours pergram of anode material).

The specific charge capacity of the silicon particles, which make uponly part of the anodes, is another parameter. Most of the anodescontain, in addition to particles of a particular type of silicon, somecombination of (i) an unknown percentage of a covalently-attachedsurface modifier (such as 2,3-dihydroxy-naphthalene or9,10-dibromoanthracene), (ii) a certain percentage of a non-covalentlyattached conductive adhesion additive (typically 9% or 10% ofcommercially available 99.5% pure C₆₀, although this additive was notadded to some anodes), and (iii) a certain percentage of a dopantadditive (typically 2% or 7% of commercially available C₆₀F₄₈, althoughthis additive was not added to many anodes). The mass of the modifierand, if present, the additives, must be subtracted from the mass of theanode, and the resulting mass of the silicon particles alone would beused in the calculation of the specific charge capacity (i.e., coin-cellcharge capacity divided by the mass of silicon particles equals thespecific charge capacity, in mAh g⁻¹, of the silicon particles in thatparticular anode in that particular coin cell).

Some of the charge/discharge cycles were performed with differentcurrent- and voltage-limit set parameters. These can be discerned byinspecting the figures showing both voltage and current vs. time (thevoltage curve is shown in red and the current curve is shown in blue inthese figures). In most cases, the voltage limits were set at 3.7 V forcharging and 2.0 V for discharging. The current limits variedconsiderably in order to test whether slow charging/discharging (i.e.,0.01 mA), at least initially, resulted in coin cells more resistant tocapacity fade than cells that were charged and/or discharged morequickly (i.e., ≥0.02 mA).

Test results indicate that charge capacity, charging rate and capacityfade are all dependent of the type of c-Si and the surface modifiersused. Examples are based on a n-type c-Si series, however p-type c-Siperforms well in some respects for both charge mobility and capacityfade. Intrinsic Si (high purity undoped) does not appear to perform aswell.

The addition of charge acceptors to functionalized c-Si composites suchas C₆₀ and possibly C₇₀ fullerenes greatly enhance the charge mobilityand therefore, the performance of the battery anodes from both chargecapacity and capacity fade perspectives. Furthermore, modified fullerenematerials (C₆₀F₄₈) exhibit significantly enhanced performance, even inlow concentrations as dopants. These results indicate that fluorinatedfullerenes and their derivatives may provide significant performance andstability when included in battery anode films made from thesurface-modified Group IVA particles. Although not wishing to be boundby theory, it is believed these additives are acting as charge mobilityimprovers, as well as binders for the composite materials. This allowsmanufacture of small format battery anodes without the need for polymersused universally by others in the industry.

Charge and discharge capacities of anodes prepared from pastes includingthe surface-modified Group IVA particles exhibit at least comparableperformance to commercial carbon anodes. Optimizing particle size,surface modification, and conductive adhesion additives/dopants mayallow for improved performance up to two orders of magnitude.

TABLE 1 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4210-2 #1I. Silicon Particles A. Type of silicon wafer used to produce theparticles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS <400 nm C. Solvent used for the grinding process Benzene D. Solventremoval methodology Vacuum distillation followed by vacuum drying for 6h at 23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 2,3-dihydroxynaphthalene B. Methodof modification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive 2wt % C₆₀F₄₈ dopant additive (previously referred to as D48 dopant) C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application paintbrush C. Anode thicknessunknown thickness D. Method of anode drying 1 hr air-dry with heat rampto 90° C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

The charge/discharge plot (0.01 mA charge/discharge current throughout)shown in FIG. 23 revealed the following for Coin Cell 4210-2 #1 asdescribed in Table 1. The initial charge capacity was 0.930 mAh. Theinitial discharge capacity was 0.364 mAh. The initial charging of thecell presumably includes the reduction of trace amounts of impurities aswell as the reduction of some electrolyte solvent molecules to form thesolid-electrolyte interface (SEI). The second charge capacity was 0.425mAh, only slightly larger than the first discharge capacity. The seconddischarge capacity was 0.339 mAh, only slightly smaller than the initialdischarge capacity.

TABLE 2 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4210-2 #2I. Silicon Particles A. Type of silicon wafer used to produce theparticles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS <400 nm C. Solvent used for the grinding process Benzene D. Solventremoval methodology Vacuum distillation followed by vacuum drying for 6h at 23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 2,3-dihydroxynaphthalene B. Methodof modification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive 2wt % C₆₀F₄₈ dopant additive C. Method of addition dichloromethane; 23(2)° C.; 10 min with sonication; air dried D. Aerobic or anaerobictreatment aerobic IV. Preparation of anode sheet A. Solvent, ratio ofsolvent to silicon particles, 1,2,3-Trichloropropane; 40 wt % solidsloading with sonication sonication B. Method of application paintbrushC. Anode thickness unknown thickness D. Method of anode drying 1 hrair-dry with heat ramp to 90° C.; 100° C.; 1 h under vacuum + 30 minfrom vacuum to atmospheric pressure E. Aerobic or anaerobic treatmentaerobic V. Coin cell assembly (strictly anaerobic) A. Cathode 0.1 mmthick × 19 mm diameter LiCoO₂ on Al substrate B. Separator film Celgard0.025 mm thick × 20 mm diameter C. Electrolyte solution EC:DMC:DEC(4:3:3) with 1M LiPF6 (+unknown proprietary additives)

The charge/discharge plot (0.01 mA charge/discharge current throughout)shown in FIG. 24 revealed that Coin Cell 4210-2 #2, as described inTable 2, has almost identical charge/discharge behavior to the previousentry, 4210-2 #1. The initial charge capacity was the same, 0.930 mAh.The initial discharge capacity was 0.391 mAh (it was 0.364 mAh for cell#1). The second charge capacity was 0.424 mAh, nearly identical to thevalue for cell #1 (0.425 mAh). The second discharge capacity was 0.355mAh, slightly higher than the value for cell #1 (0.364 mAh).

TABLE 3 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4D10-0 I.Silicon Particles A. Type of silicon wafer used to produce the particles0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS < 400 nm C.Solvent used for the grinding process Benzene D. Solvent removalmethodology Vacuum distillation followed by vacuum drying for 6 h at23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 9,10-dibromoanthracene B. Method ofmodification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive nodopant additive C. Method of addition dichloromethane; 23(2) ° C.; 10min with sonication; air dried D. Aerobic or anaerobic treatment aerobicIV. Preparation of anode sheet A. Solvent, ratio of solvent to siliconparticles, 1,2,3-Trichloropropane; 40 wt % solids loading withsonication sonication B. Method of application Automated film applicatorC. Anode thickness 0.100 mm D. Method of anode drying 1 hr air-dry withheat ramp to 90° C.; 100° C.; 1 h under vacuum + 30 min from vacuum toatmospheric pressure E. Aerobic or anaerobic treatment aerobic V. Coincell assembly (strictly anaerobic) A. Cathode 0.1 mm thick × 19 mmdiameter LiCoO₂ on Al substrate B. Separator film Celgard 0.025 mm thick× 20 mm diameter C. Electrolyte solution EC:DMC:DEC (4:3:3) with 1MLiPF6 (+unknown proprietary additives)

The mass of the anode in Coin Cell 4D10-0 of Table 3 was ca. 7 mg.Therefore, the initial coin-cell charge capacity, extrapolated to 0.062mAh from the logarithmic fit to these data as shown in FIG. 25,translates into an initial specific charge capacity of 8.9 mAh g⁻¹ forthis anode material. The capacity fade is less than 10% over these 58cycles as shown in FIG. 26.

TABLE 4 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4D10-2 #1I. Silicon Particles A. Type of silicon wafer used to produce theparticles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS <400 nm C. Solvent used for the grinding process Benzene D. Solventremoval methodology Vacuum distillation followed by vacuum drying for 6h at 23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 9,10-dibromoanthracene B. Method ofmodification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive 2wt % C₆₀F₄₈dopant additive (previously referred to as D48 dopant) C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application Film Applicator C. Anode thickness0.100 mm D. Method of anode drying 1 hr air-dry with heat ramp to 90°C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

The mass of this anode in Coin Cell 4D10-2 #1 of Table 4 was ca. 7 mg.Therefore, the nominal coin-cell charge capacity of 0.04 mAh from cycle15 through cycle 41 translates into a specific charge capacity of 5.7mAh g⁻¹ for this anode material, as shown in FIG. 27. The capacity fadeappears to be insignificant after cycle 15 as shown in FIG. 28.

TABLE 5 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4D10-2 #2I. Silicon Particles A. Type of silicon wafer used to produce theparticles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS <400 nm C. Solvent used for the grinding process Benzene D. Solventremoval methodology Vacuum distillation followed by vacuum drying for 6h at 23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 9,10-dibromoanthracene B. Method ofmodification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive 2wt % C₆₀F₄₈ dopant additive (previously referred to as D48 dopant) C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application Film Applicator C. Anode thickness0.100 mm D. Method of anode drying 1 hr air-dry with heat ramp to 90°C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

Table 5 shows Coin Cell 4D10-2 #2. FIGS. 29 and 30 show the performancedata for the coin cell.

TABLE 6 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4D10-2 #3I. Silicon Particles A. Type of silicon wafer used to produce theparticles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS <400 nm C. Solvent used for the grinding process Benzene D. Solventremoval methodology Vacuum distillation followed by vacuum drying for 6h at 23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 9,10-dibromoanthracene B. Method ofmodification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive 2wt % C₆₀F₄₈ dopant additive (previously referred to as D48 dopant) C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application Film Applicator C. Anode thickness0.100 mm D. Method of anode drying 1 hr air-dry with heat ramp to 90°C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

Table 6 shows Coin Cell 4D10-2 #3. FIGS. 31 and 32 show the performancedata for the coin cell.

TABLE 7 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4D10-2 #4I. Silicon Particles A. Type of silicon wafer used to produce theparticles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS <400 nm C. Solvent used for the grinding process Benzene D. Solventremoval methodology Vacuum distillation followed by vacuum drying for 6h at 23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 9,10-dibromoanthracene B. Method ofmodification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀ conductive adhesion additive B. Dopant additive 2wt % C₆₀F₄₈ dopant additive (previously referred to as D48 dopant) C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application Film Applicator C. Anode thickness0.100 mm D. Method of anode drying 1 hr air-dry with heat ramp to 90°C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

Table 7 shows Coin Cell 4D10-2 #4. FIGS. 33 and 34 show the performancedata for the coin cell.

TABLE 8 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 429-0 I.Silicon Particles A. Type of silicon wafer used to produce the particles0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS < 400 nm C.Solvent used for the grinding process Benzene D. Solvent removalmethodology Vacuum distillation followed by vacuum drying for 6 h at23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 2,3-dihydroxynaphthalene B. Methodof modification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 9 wt % C₆₀ conductive adhesion additive B. Dopant additive nodopant additive C. Method of addition dichloromethane; 23(2) ° C.; 10min with sonication; air dried D. Aerobic or anaerobic treatment aerobicIV. Preparation of anode sheet A. Solvent, ratio of solvent to siliconparticles, 1,2,3-Trichloropropane; 40 wt % solids loading withsonication sonication B. Method of application Film Applicator C. Anodethickness 0.200 mm D. Method of anode drying 1 hr air-dry with heat rampto 90° C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

The anode mass of Coin Cell 429-0 of Table 8 is probably ca. 7 mg. Thespecific charge capacity of the anode material during the third cycle isca. 11 mAh g⁻¹ as shown in FIG. 35. The capacity fade is quitesignificant as shown in FIG. 36.

TABLE 9 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4210-7 I.Silicon Particles A. Type of silicon wafer used to produce the particles0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B. Particle Size APS < 400 nm C.Solvent used for the grinding process Benzene D. Solvent removalmethodology Vacuum distillation followed by vacuum drying for 6 h at23(2) ° C. E. Treatment with or without aq. HF or anhydrous HF Nottreated with HF F. Aerobic or anaerobic treatment of silicon particlesAerobic II. Surface Modification (covalently attached aromatichydrocarbon derivatives) A. Modifier 2,3-dihydroxynaphthalene B. Methodof modification 20 wt %; triglyme reflux (216° C.) for 6 h C. Aerobic oranaerobic treatment aerobic III. Addition of non-covalently-attachedconductive adhesion and/or dopant additives A. Conductive adhesionadditive 10 wt % C₆₀conductive adhesion additive B. Dopant additive 7 wt% C₆₀F₄₈ dopant additive (previously referred to as D48 dopant) C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application paintbrush C. Anode thicknessunknown thickness D. Method of anode drying 1 hr air-dry with heat rampto 90° C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

Coin Cell 4210-7 of Table 9 has excellent charge capacity but onlymarginal fade characteristics as shown in FIGS. 37 and 38. Taking thecoin cell charge capacity after the first 10 cycles, 0.319 mAh, thespecific charge capacity of this anode material, assuming that the anodeweighed ca. 7 mg, is ca. 46 mAh g⁻¹. Note that the theoretical specificcharge capacity of silicon, ca. 4,000 mAh g⁻¹, is ca. 87 times higher.However, the amount of silicon in this anode is almost certainly 20+%lower than 7 mg (it contains 10% C₆₀ conductive adhesion additive, 7%C₆₀F₄₈ dopant additive, and an unknown amount of 2,3-DHN surfacemodifier). Therefore, the specific charge capacity of the silicon inthis anode material is probably ca. 58 mAh g⁻¹. Furthermore, that is thespecific charge capacity after 10 cycles, during which time the celllost more than 25% of the charge capacity during the second cycle.Calculating the specific charge capacity of the silicon in the anodebased on that, it is ca. 76 mAh

TABLE 10 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 1210-0 #1and Coin Cell 1210-0 #3 I. Silicon Particles A. Type of silicon waferused to produce the particles 99.5% pure intrinsic silicon B. ParticleSize APS < 400 nm C. Solvent used for the grinding process Benzene D.Solvent removal methodology Vacuum distillation followed by vacuumdrying for 6 h at 23(2) ° C. E. Treatment with or without aq. HF oranhydrous HF Not treated with HF F. Aerobic or anaerobic treatment ofsilicon particles Aerobic II. Surface Modification (covalently attachedaromatic hydrocarbon derivatives) A. Modifier 2,3-dihydroxynaphthaleneB. Method of modification 20 wt %; triglyme reflux (216° C.) for 6 h C.Aerobic or anaerobic treatment aerobic III. Addition ofnon-covalently-attached conductive adhesion and/or dopant additives A.Conductive adhesion additive 10 wt % C₆₀ conductive adhesion additive B.Dopant additive no dopant additive C. Method of additiondichloromethane; 23(2) ° C.; 10 min with sonication; air dried D.Aerobic or anaerobic treatment aerobic IV. Preparation of anode sheet A.Solvent, ratio of solvent to silicon particles, 1,2,3-Trichloropropane;40 wt % solids loading with sonication sonication B. Method ofapplication Automated film applicator C. Anode thickness 0.100 mm D.Method of anode drying 1 hr air-dry with heat ramp to 90° C.; 100° C.; 1h under vacuum + 30 min from vacuum to atmospheric pressure E. Aerobicor anaerobic treatment aerobic V. Coin cell assembly (strictlyanaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ on Alsubstrate B. Separator film Celgard 0.025 mm thick × 20 mm diameter C.Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

Coin Cell 1210-0 #1 of Table 10 had still not reached 3.7 V after manyhours; the voltage seemed to have stabilized at ca. 3.6 V and continuedto charge. The voltage limit was changed to 3.6 V and the cell wasrestarted. It was still charging at 0.0075 mA after an additional 20 h.Coin Cell 1210-0 #3 exhibited essentially the same behavior, and thesame voltage-limit switch was made. The only difference was that it wasstill charging at 0.0131 mA after the additional 20 h. Note, 0.02 mA forconstant current phases; down to 0.005 mA for constant voltage phaseduring charging.

TABLE 11 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 4210-0 #1and Coin Cell 4210-0 #3 I. Silicon Particles A. Type of silicon waferused to produce the particles 0.4-0.6 Ω cm⁻¹ P-doped (n-type) silicon B.Particle Size APS < 400 nm C. Solvent used for the grinding processBenzene D. Solvent removal methodology Vacuum distillation followed byvacuum drying for 6 h at 23(2) ° C. E. Treatment with or without aq. HFor anhydrous HF Not treated with HF F. Aerobic or anaerobic treatment ofsilicon particles Aerobic II. Surface Modification (covalently attachedaromatic hydrocarbon derivatives) A. Modifier 2,3-dihydroxynaphthaleneB. Method of modification 20 wt %; triglyme reflux (216° C.) for 6 h C.Aerobic or anaerobic treatment aerobic III. Addition ofnon-covalently-attached conductive adhesion and/or dopant additives A.Conductive adhesion additive 10 wt % C₆₀ conductive adhesion additive B.Dopant additive no dopant additive C. Method of additiondichloromethane; 23(2) ° C.; 10 min with sonication; air dried D.Aerobic or anaerobic treatment aerobic IV. Preparation of anode sheet A.Solvent, ratio of solvent to silicon particles, 1,2,3-Trichloropropane;40 wt % solids loading with sonication sonication B. Method ofapplication Automated film applicator C. Anode thickness 0.100 mm D.Method of anode drying 1 hr air-dry with heat ramp to 90° C.; 100° C.; 1h under vacuum + 30 min from vacuum to atmospheric pressure E. Aerobicor anaerobic treatment aerobic V. Coin cell assembly (strictlyanaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ on Alsubstrate B. Separator film Celgard 0.025 mm thick × 20 mm diameter C.Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

Coin Cell 4210-0 #1 of Table 11 had not reached 0.005 mA during thefirst constant voltage (3.7 V) phase after 27 h. Coin Cell 4210-0 #3 ofTable 11 had not reached 3.7 V during the first constant current phaseafter 17 h. Note, 0.02 mA for constant current phases; down to 0.005 mAfor constant voltage phase during charging.

TABLE 12 Lithium-Ion Coin Cell Fabrication Variables Coin Cell 5210-0#1; Coin Cell 5210-0 #2; Coin Cell 5210-0 #3 I. Silicon Particles A.Type of silicon wafer used to produce the particles 0.014-0.017 Ωcm⁻¹B-doped (p-type) silicon B. Particle Size APS < 400 nm C. Solventused for the grinding process Benzene D. Solvent removal methodologyVacuum distillation followed by vacuum drying for 6 h at 23(2) ° C. E.Treatment with or without aq. HF or anhydrous HF Not treated with HF F.Aerobic or anaerobic treatment of silicon particles Aerobic II. SurfaceModification (covalently attached aromatic hydrocarbon derivatives) A.Modifier 2,3-dihydroxynaphthalene B. Method of modification 20 wt %;triglyme reflux (216° C.) for 6 h C. Aerobic or anaerobic treatmentaerobic III. Addition of non-covalently-attached conductive adhesionand/or dopant additives A. Conductive adhesion additive 10 wt % C₆₀conductive adhesion additive B. Dopant additive no dopant additive C.Method of addition dichloromethane; 23(2) ° C.; 10 min with sonication;air dried D. Aerobic or anaerobic treatment aerobic IV. Preparation ofanode sheet A. Solvent, ratio of solvent to silicon particles,1,2,3-Trichloropropane; 40 wt % solids loading with sonicationsonication B. Method of application Automated film applicator C. Anodethickness 0.100 mm D. Method of anode drying 1 hr air-dry with heat rampto 90° C.; 100° C.; 1 h under vacuum + 30 min from vacuum to atmosphericpressure E. Aerobic or anaerobic treatment aerobic V. Coin cell assembly(strictly anaerobic) A. Cathode 0.1 mm thick × 19 mm diameter LiCoO₂ onAl substrate B. Separator film Celgard 0.025 mm thick × 20 mm diameterC. Electrolyte solution EC:DMC:DEC (4:3:3) with 1M LiPF6 (+unknownproprietary additives)

FIGS. 39-41 show charge/discharge cycles for the coin cells of Table 2.Coin Cell 5210-0 #1 showed the following performance: 1^(st) cycle:charge capacity=0.119 mAh; discharge capacity=0.029 mAh; 2^(nd) cycle:charge capacity=0.037 mAh; discharge capacity=0.026 mAh; 3^(rd) cycle:charge capacity=0.069 mAh; discharge capacity=0.037 mAh; and 4^(th)cycle: charge capacity=0.027+ mAh (not finished charging at this time).Coin Cell 5210-0 #2 showed the following performance: 1^(st) cycle:charge capacity=0.116 mAh; discharge capacity=0.029 mAh; 2^(nd) cycle:charge capacity=0.034 mAh; discharge capacity=0.027 mAh; and 3^(rd)cycle: charge capacity=0.031 mAh; discharge capacity=0.026 mAh. CoinCell 5210-0 #3 showed the following performance: 1^(st) cycle: chargecapacity=0.130 mAh; discharge capacity=0.034 mAh; and 2^(nd) cycle:charge capacity=0.041 mAh; discharge capacity=0.031 mAh.

Tables 13 and 14 show the coin cell data charge capacity, dischargecapacity, specific charge capacity, and fade, in a summarized fashion.The data in Table 14 is intended to compare the surface modificationtrends, all with the same n-type silicon base. As the surface modifiergrows in size, there is observed a reduction of resistivity and anincrease in specific charge capacity.

TABLE 13 * CCC/CVC (wet) film Charge Discharge Spec. Charge AnodeV_(max)/V_(min) thickness/ Capacity Capacity Capacity Cap. Fade Formula(mA)/(V) mass (mg) (mAh) (mAh) (mAh/g) # cycles 4210-2 0.010/0.003 0.100mm 0.425 0.364 80.1 11% #2 3.70 V/2.00 V 5.3 3 4210-2 0.010/0.003 0.100mm 0.424 0.355 80.0 11% #4 3.70 V/2.00 V 5.3 3 4210-0 0.020/0.005 0.100mm 0.368 0.334 62.4  6% #1 3.70 V/2.00 V 5.9 2 4210-0 0.020/0.005 0.100mm 0.232 0.193 39.3 27% #3 3.70 V/2.00 V 5.9 3 5210-0 0.020/0.005 0.100mm 0.051 0.042 8.6 14% #1 3.70 V/2.00 V 5.9 20 5210-0 0.020/0.005 0.100mm 0.069 0.050 11.7   0%^(†) #2 3.70 V/2.00 V 5.9 14 1210-0 0.020/0.0050.100 mm 0.059 0.053 10.0 30% #1 3.60 V/2.00 V 5.9 14 1210-0 0.020/0.0050.100 0.110 0.095 18.6 40.7 #3 3.60 V/2.00 V 5.9 4 4610-0 0.02 mA/unknown 0.062 0.06 8.9 10% #2 3.70 V/2.75 V ~7 mg 60 4610-2 0.02 mA/ 0.100 mm/ 0.05 0.04 5.7 30% #1 3.70 V/2.75 V  7 mg 45 429-0 0.02 mA/ 0.200 mm/ 0.13 0.075 10.8 20% #4 3.70 V/2.00 V 12 mg 20 CMS 0.02 mA/ 0.05 mm 0.826 0.755 51.6 16% graphite 3.7 V/2.0 V (dry)/ 3 anode 16mg * Anode formulae: 1***-*: (intrinsic) 99.5%; 325 mesh (Alpha Aesar)CAS# 7440-21-3 4***-*: (n-type); P-doped wafer; Resist. = 0.4-0.6 Ω cm⁻¹5***-*: (p-type); B-doped wafer; Resist. = 0.014-0.016 Ω cm⁻¹ Cathodeformula: LiCoO₂ Solvent/Electrolyte: EC:DMC:DEC (4:3:3 by vol.)/LiPF6(1M) **CCC: Constant Current Charge CVC: Constant Voltage ChargeV_(max): Charging voltage limit V_(min): Discharge voltage limit^(†)charge capacity increased during the first few cycles; insufficientcycles have been acquired to show capacity fade.

TABLE 14 * CCC/CVC (wet) film Charge Discharge Spec. Charge AnodeResist. V_(max)/V_(min) thickness/ Capacity Capacity Capacity Cap. FadeFormula MΩ/cm (mA)/(V) mass (mg) (mAh) (mAh) (mAh/g) # cycles 4210-00.020 0.020/0.005 0.100 mm 0.368 0.334 62.4  6% #1 3.70 V/2.00 V 5.9 24110-0 0.180 0.020/0.005 0.100 mm 0.347 0.323 42.8 #3 3.70 V/2.00 V 8.14B >40 0.020/0.005 0.100 mm 0.043 0.033 14.8  0%^(†) #1 3.70 V/2.00 V2.9 11 4610-0 9.8 0.020/0.005 0.100 mm 0.051 0.034 14.1 35% #1 3.70V/2.00 V 3.6 11 CMS Not 0.02 mA/  0.05 mm 0.826 0.755 51.6 16% graphitemeas. 3.7 V/2.0 V (dry)/ 3 anode 16 mg 4B*** = n-type c-Si surfacepassivated wit benzene only. 4110-0 = n-type c-Si surface modified withcatechol (dihydroxy benzene) 4210-0 = n-type c-Si surface modified withdihydroxy naphthalene.

Example 6 Comparison to Carbon Anode

FIG. 42 shows a comparison of lithium-ion batteries having anodesprepared with functionalized Group IVA particles versus batteriesprepared with a standard carbon based anode. Performance of thecarbon-based anode is shown in red, performance of anodes preparedaccording to the present invention are shown in purple and green. Asshown, the batteries of 4210-0 and 4210-2 outperformed the standardcarbon based anode.

Example 7 Prediction of Specific Charge Capacity

FIG. 43 shows that there appears to be a correlation such that Si can betested prior to fabricating batteries to predict based on resistance ofthe Si, what the specific charge capacity, mAh/g will be.

It is understood that the foregoing detailed description andaccompanying examples are merely illustrative and are not to be taken aslimitations upon the scope of the invention, which is defined solely bythe appended claims and their equivalents.

Various changes and modifications to the disclosed embodiments will beapparent to those skilled in the art. Such changes and modifications,including without limitation those relating to the chemical structures,substituents, derivatives, intermediates, syntheses, compositions,formulations, or methods of use of the invention, may be made withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A lithium ion battery comprising a positiveelectrode; a negative electrode comprising a composite comprising atleast one submicron functionalized Group IVA particle; a lithium ionpermeable separator between the positive electrode and the negativeelectrode; a solvent that is a mixture of at least ethylene andpropylene carbonates; and an electrolyte comprising lithium ions.
 2. Thelithium ion battery of claim 1, wherein the composite is a porouscovalent framework that is a covalent organic framework, a metal organicframework, or a zeolitic imidazolate framework.
 3. The lithium ionbattery of claim 2, wherein the porous covalent framework is a2-dimensional framework.
 4. The lithium ion battery of claim 2, whereinthe porous covalent framework is a 3-dimensional framework.